Mass mortality fish kill is very unlikely to be due to climate change (temperature rise and pH lowering) these events are too slow and usually teh biota adapt to these changes to some extent, it can lead to stress but not necessarily mortality. saying that these temp increase and availability of CO2 in water can lead to algal bloom which inturn can create eutrophication and fish kill.

Dear Saif,

Yes eutrophication could be one of the reasons of fish kills. Did you record any causes of fish kills in water bodies in Kuwait? Please let me know

Dear Colleagues,

What do you think about climate change effects on occurrence of new emerging and re-merging fish diseases in Marine fish?

1) Domestic sewage entering a city lake produced too much of algae,which depleted DO2 during night time, leading to mass mortality of fish. This increase in algal mass occurred during the month of May when sunlight intensity was the maximum as compared to other months of the year.

2) Regular bird droppings enhanced PO4 content in a fish farm, where brooders were kept, & this lead to algal blooms,depleting DO2, leading to steady mortality.

3) Sudden rise of day temperature lead to killing young ones of ribbon fish, especially near coastal surf zone. This happens regularly in Sept-Oct when the difference in range of night time & day time temperatures lengthens.

Dear Jalil,

I do agree with you that prevalence of diseases and parasites will enhance in a warming world

Dear Chandravadan,

Thank you for your inputs referring to fish kills in India related to sewage effluents (Low DO), phosphate inputs (via bird droppings) and rise of temperature. Do you keep a record when it occurred?

We have observed massive fish kill in Kuwaiti waters in 2001, 2004, 2009, 2011, they are very well studied, documented there was an infection on one incidence, eutroiphication due to algal bloom on other ocassions. But the fishes have adjusted themselves to the prevaling environmental conditions and there are no stresses recorded until the catastrophe. To cite an example a study was done for HSP 70 and the expression was during winters rather than summer months, suggesting that the fishes express this protein during lowering of temperature rather than high temperatuer as seen elsewhere in the world.

Dear Saif,

What about occurrence of Viral Nervous Necrosis (VNN) mortality in marine fish of your coastal region? as you know Grouper and Mullet (Mugil cephalus) are very sensitive to mentioned emerging disease in other region.

It would be high appreciated if you inform me about mentioned mortality record.

Kind regards

Dear Saif, thank you

Noted incidences related to infection and eutrophication and heat shock protein (during winter)

Dear Jalil,

I have summarised some info about VNN (see below-perhaps you already knows about it?), which indicate that VNN is distributed in many continents. In addition to marine fish it also infects some freshwater fish as well!

Viral nervous necrosis (VNN), also known as viral encephalopathy and retinopathy (VER), is an important, emerging group of fish diseases caused by the betanodaviruses. The betanodaviruses are an important, emerging group of viruses known to infect over 40 marine fish species worldwide, including populations in Australia, Asia, Europe, North America, Africa, and the South Pacific.

Currently, there are four species of betanodavirus based on genetic analyses: a) Striped jack nervous necrosis virus (SJNNV); b) Barfin flounder nervous necrosis virus (BFNNV); c) Tiger puffer nervous necrosis virus (TPNNV); and d) Redspotted grouper nervous necrosis virus (RGNNV).

Numerous marine finfish and some freshwater species worldwide have been reported to be susceptible to the betanodaviruses, with mortalities as high as 100%. Marine food and game fishes include red drum (Sciaenops ocellatus), cobia (Rachycentron canadum), sea bass (Dicentrachus labrax), barramundi (Lates calcarifer), gilthead seabream (Sparus aurata), Pacific bluefin tuna (Thunnus orientalis), various grouper species (Family Serranidae), and various flatfish species, including halibut (Hippoglossus hippoglossus) and Japanese flounder (Paralichthys oliveatus).

Susceptible freshwater species include tilapia (Oreochromis niloticus) and the ornamental fish the guppy (Poecilia reticulata). The virus can be spread from infected diseased fish, wild invertebrates, contaminated live or frozen foods, contaminated water, and carrier (subclinical) broodstock source: http://edis.ifas.ufl.edu/fa180

Dear Wayne, Thank you for sending through the list of publications. I had a quick read about the damaging impacts of sewage outflows on Buffalo Creek (Northern Australia). Low dissolved oxygen, high level of nutrients, algal blooms, a specific chemical compound found in the creeks but had not major fish kills, apparently due to dilution effects (incoming tides)

Dear All,

The answer is pollution.

The 2000 Baia Mare cyanide spill was the biggest tragedy of the rivers and the fishes in Hungary. It was the consequence of a leak of cyanide near Baia Mare, Romania, into the Someş River by the gold mining company Aurul, a joint-venture of the Australian company Esmeralda Exploration and the Romanian government.

The polluted waters eventually reached the Tisza and then the Danube, killing large numbers of fish in Hungary and in former Yugoslavia. The spill has been called the worst environmental disaster in Europe since the Chernobyl disaster.

Five weeks later, a spill of contaminated waters (this time with heavy metals) hit the region. A dyke burst in Baia Borşa, Maramureş County and 20,000 cubic metres of zinc, lead and copper-contaminated water made its way into the Tisza.

A year later, another cyanide spill occurred in Romania, this time being a deliberate emptying of cyanide solutions into the Siret River.

http://en.wikipedia.org/wiki/2000_Baia_Mare_cyanide_spill

Three attempts were made in the Romanian Parliament to ban gold cyanidation in Romania, none of which being successful so far.

Romania refused to pay a compensation for the damage caused.

Dear András,

Many many thanks for providing info about the worst environmental disaster (major fish kills) in Hungary/Yugoslavia (Somes River in 2000) related to leakage of cyanide and associated toxic metals (Zn, Pb, Cu) from gold mining.

I have summarized the impacts based on your information and links as follows:

• The cyanide concentrations in the River had > 700 times the permitted levels.

• The disaster contaminated the drinking water supplies of over 2.5 million Hungarians

• In some of the Serbian section, about 80% of the aquatic life was killed

• The toxicity of cyanide caused major fish kills affecting 62 species of fish (20 of which are protected species)

• As a consequence of the cyanide disaster (which caused the mass fish kill and aquatic life), few environmental groups (e.g. Friends of the Earth and Greenpeace) suggested banning of old mining with cyanides

• There were three attempts in the Romanian Parliament to ban gold cyanidation in Romania

Some facts about cyanide toxicity

Fish have been shown to be the most sensitive aquatic organism, followed by invertebrates to cyanide. Fish are one thousand times more sensitive to cyanide than human. Birds and other wildlife can also be potentially at risk from cyanide poisoning if they are using tailings ponds for drinking or swimming

You mentioned upwelling as a fish killer, but upwelling causing algal blooms especially silicoflagellate blooms that are characteristic for marine upwelling area. Thay are causing physical demage on fish branchiae what inducing in their mortality. Most of that kind of in situ killing we can find in the geological past too!

Dear Ines,

Thank you for information related to fish kills related to silcoflagellates.

It is reported that silicoflagellates are most abundant in areas of upwelling and equatorial waters. Upwelling provide silica-rich deep water to siliceous organisms in the photic zone, thus influence their abundance.

A recent report of mariculture mortality (farmed salmon) attributed to a silicoflagellate bloom in Danish waters, where farmed salmon (Salmo salar) and trout (Salmo gairdneri) died during blooms of the naked cell stage of Dictyocha speculum. Though silicoflagellates occur in all oceans (Mesozoic through the Cenozoic) but are generally of low overall abundance in present day seas. They were plentiful in the fossil records.

According to some reports, the species, Dictyocha speculum may produce toxins, and may also cause mechanical irritation at high concentrations. Skeletal forms in concentrations of ∼400 cells mL to 1000 cells mL-1 have been recorded to kill fish. The skeletons irritate the gills, causing them to produce mucus, and eventually causing suffocation/asphyxiation.

While toxic discharges in water bodies may explain certain massive fish kill events, most events are likely the result of eutrophication. Since the early 60-ties of last century the global fixation of N2 into fertiliser nitrogen has steeply increased, to an extend that today's antropogenic input of reactive nitrogen (via fertliser) exceeds that of natural N2 fixation. The result is massive eutrophication, which triggers the development of algae (and of water weeds like water hyacinth). Algal blooms may have two distinct effects in water bodies: a) some algae and cyanobacteria produce toxins that cause fish kill, and b) during the dark period (night time) algea consume oxygen from the water column, creating anoxic conditions which may cause massive fish kills. Its high time we revisit the green revolution.

Dear Huub,

Yes, nutrients from agriculture have been a source of eutrophication in water bodies. Oxygen depletion is the most common cause of fish kills.

In some parts of West Virginia the most frequently suspected cause is P related blooms. However, often fish kills are over reported. For example a report of a large fish kill is made, officials investigate and find very few fish but the "event" makes the news. At other times, researchers document real fish kills and they may go unnoticed. Often i don't think they know the cause. Some kills are obvious (AMD in some parts of WV) and some less obvious (unknown chemical impacts).

Dear Michael,

Thank you for letting to know that some fish kills occurred in west Virginia, USA that were related to nutrients (P) and algal blooms and AMD

The lack of oxygen in the internal lakes during warm days of the summer represents the most important cause of the fish death in my Country.

Dear Gabriel,

Thank you for info related to fish kills in Romanian lakes due to low dissolved oxygen

There are various reason have been mentioned already including toxicological agents and ecological parameters. I would like to mention about dynamite blast used in river Mahanadi for killing fish specially in rocky bed of river. Management people is taking all sort of measure to control this. Visit the following link.

http://www.telegraphindia.com/1101217/jsp/orissa/story_13309265.jsp

Dear Soma, Many thanks for the interesting links which tells the story about use of dynamite in Mahandi River, the practice of which is a threat to some of rare fish species of the river. Can you find out about those rare fish species? Also is it legal or illegal to use dynamite in India?

Dear Golam, It is illegal ofcourse. but some of the fishermen use this practice as it is difficult to operate gear in the rocky pools. This practice has been observed in the upstreams only because of the above mentioned reason. It is again difficult to identify fish species caught in dynamite blast because of deformities occur due to blast. Mostly cyprinids are affected. There may be many other fishes also.

Уважаемый голам, у нас в прошлом году наблюдалась массовая гибель рыбы на горьковском водохранилище. Как началась жара с июля там начала наблюдаться гибель рыбы. При этом, что интересно содержание кислорода в воде в норме по рыбохозяйственным нормативам. Связываю это с массовым цветением синезеленых водорослей.

Dear Valdimr,

Thank you for your inputs related to massive fish kills in Gorkovsky reservoir, Russia related to algal blooms

Dear Jacklin,

Eutrophication is one of the causes of fish kills. Was there any fish kills in lakes in India related to eutrophication in recent time or in the past? Any links or evidences (references) will be helpful

Up here in the north, Fennoscandia in this case, where lakes freeze over during the winter, the most common cause of fish kills is probably late winter anoxia under the ice cover. Such events mainly occur when climatic conditions are unfavorable: eutrophic lakes, small ponds during low water level years, in cases when lakes freeze over quickly while the water mass is still relatively 'warm' and poorly mixed in the lower parts etc.

A specific case of the AMD effects that you mentined in your question is the 'seasonal internal loading of dissolved reduced metals'. In these cases metals (mining-derived or otherwise) are released from sediments into the hypolimnion during the winter anoxia. During the spring turnover, this metal-rich water mass starts to oxidize from the top down. This creates a zone of low pH because metal (iron) precipitation produces acidity. However, fish kills caused by this mechanism are very rare.

Dear Jacklin,

Yes livestock effluents/wastes can lead to fish kills

Dear Tommi,

Thank you for informing that some of fish kills in Finland are/may be associated with anoxia, AMD

In central Switzerland "accidental" spills of liquid manure cause every year several fish kills in streams.

Dear Gachter,

Thank you for informing that in Switzerland accidental spills of liquid manure causes fish kills on a regular basis. In Australia, there is stringent protocol about managing livestock manures for two reasons: water quality and fish kills,.

In some Iraqi lake (Habbaniyah lake) and fish ponds, Microcystis spp blooming causes fish kills.

Also here in Fennoscandia fish kills can occur during summer because of anoxia. In one paper (http://www.borenv.net/BER/pdfs/ber17/ber17-398.pdf) we have reported collapse of smelt stock in boreal lake due to high temperature in epilimnion and anoxia in hypolimnion. Thus the fish adapted to cold water were forced to occupie warm epilimnion leading to coööapse of that stock.

In very rural areas in Bangladesh, fish mortality occurs in backyard and/or homestead farming during monsoon what is likely caused by sudden sharp changes in water parameter by rainfall and subsequent influx of wastes i.e. livestock manures, agricultural wastes, into the pond through rain-water flushing.

Dear Fikrat,

Thank you for the information that blue green algae/cyanobacteria Microcystsis spp are responsible for fish kills

Dear Tapio,

Thanks for the paper which highlights that climate change (global warming) might be a threat on smelt populations and may cause fish kills and even extinction of the species (related to rise of temperatures and anoxic/low DO) etc

Dear Abul Farah,

Yes significant rainfalls can wash down wastes including livestock manures and other agricultural wastes into ponds/dams /lakes. For example, manures contains ammonia which could be highly toxic to fish. Similarly, nutrients (N,P) sources from manures and other agricultural wastes can stimulate algal blooms and lower DO as they decompose. All of these can lead to fish kills

Hi,

I have noticed a fish kill around a barge immediately after landing in Saudi Arabia for an assignment as a water specialist in Royal Commission Environmental Monitoring Laboratories, Yanbu-Al-Sinaiyah. Physico-chemical parameters were all normal, there was no algal bloom either in the waters. This led me to look for other parameters such as tide, atmospheric temperature, wind speed etc. It was found that the day fish kill happened was also the day when the tide was at its lowest, atmospheric temperature was also the lowest and also the wind speed the highest for the season. We presumed that these factors might have contributed to sudden lowering of water temperature around the barge and since fishes were trapped here without a means to escape to the open seas, could have died due to sudden lowering of water temperature.

Dear Valsaraj,

An important observation

Do you know when (date) fish kill occurred, also what could have been the water temperature? Is it a common cause of fish kill in Saudi Arabia? Thanks

I think it was on November 21 or 22, 1992. As I have written it was just after I landed up there. I was not holding the National Residence Permit (IQAMA as the locals say) and my company advised me not to venture out till they obtain the permit for me. Therefore I was not present during the first inspection. I could visit the site only a day after the event. I had given a set of guidelines to be followed in such cases. For e.g., knowing the sex of fish that died could give a clue. For e.g., if only female fish had died we should examine for ovarian disease, etc. Looking for gut content was another to see if toxic organisms are present for likely cause and many other such directions.

I am sorry that I do not have data on water temperature as such because there was no monitoring. The data on wind speed and atmospheric temperature could be collected as we were continuously monitoring the same in about 5 air quality monitoring stations in Yanbu. My suspicion is the combined action of lowering in water level, atmospheric temperature and increased wind speed could have drastically reduced the water temperature around the barge which is cut of from surrounding oceanic waters due to placement of huge boulders. When I discussed this with the marine biologists there, they told me it happens almost every year during that part of the year. This was actually the reason for me to suspect sudden shift in temperature and what little data we had pointed to such strong possibility.

I think I have also answered your last question. Still I would like to emphasize that this is a very localized event (around a barge) and we should not relate this to any other fish kills that could have occurred in Saudi Arabia.

Dear Valsaraj,

Than you for the additional information and your time.

I think pollution is the main root cause. Water contamination is increasing rapidly due to unplanned industrialization and urbanization. Especially, chemical factories near water resources are mixing untreated water into lakes, rivers, coastal waters and oceans which cause fish kills.

What about high tech fishing techniques causing over-exploitation of fish resources?

@Marcel M. Lambrechts, YES that is absolutely correct. It is also a factor that I missed, Thanks for pointing to it.

Dear Asmat,

Yes chemical pollution is one of the causes!

Dear Marcel,

Use of high tech fishing can cause overfishing which may result an increase of bycatch (non-wanted/used) and non-targeted organisms. The unwanted species are generally discarded as dead!

Dear Golam,

It is disturbing if chemical pollution happens to be the more common cause for fish kills. Why I am saying this is because for every fish that dies due to lethal dose of the pollutant, hundreds more in the fringe region which do not get exposed to the lethal dose but nevertheless are exposed to the pollutant accumulates these and store in inert sites so they themselves are not threatened. However, if humans consume such fishes they are exposed to sudden high concentrations of pollutant and may even die. The famous Minamata disease is a grim reminder. So all the more reason that we all should highlight fish kills due to chemical pollution and educate the public about the same.

Dear Valsaraj,

Yes some pollutants (pesticides, metals) are bio-accumulative and can be transferred via the food chain pathways to humans!

I agree with Marcel. Excessive fishing activity cause recruitment over fishing and growth over fishing. Thus affect the fish catch from open water system. More destructive gear like Bottom Trawl net never leave juveniles also.

@Golam Kibria, thanks for taking note of the point.

Anoxic conditions occurred mainly in stratified enclosed areas can lead in massive fish death. Eutrophication: e.g. high amounts of nutrients discharging from rivers to their estuaries and coastal marine areas due to extreme rain events, may lead to drastic changes of N:P ratio and finally to toxic algal blooms (HABs). Toxic species could also kill fish. In Greece, in Malliakos gulf, sudden discharge of nutrients from Sperchios river due to high precipitation, caused massive fish death due to the growth of fish toxic species "Chattonella". Additionally, high levels of chemicals toxics could also kill fish.

Dear Alexandra,

Yes toxic "Chattonella" spp. can cause fish kills. In Japan, the species caused massive kill of yellowtail, Seriola quinqueradiata.

Daekyung KIM and Tatsuya ODA. 2010. Possible Factors Responsible for the Fish-Killing Mechanisms of the Red Tide Phytoplankton, Chattonella marina and Cochlodinium polykrikoides. Coastal Environmental and Ecosystem Issues of the East China Sea. Eds., A. Ishimatsu and H.-J. Lie, pp. 245–268.

Dear Golam,

thank you for your answer and the very useful information.

Growth of Algae such as Cyanophyceae (Microcystis)and illegal use of posinces by fishermen

In the Pantanal, one of the largest freshwater floodplain in the world, fish kills is a natural phenomenon that can occur every year, as a result of the flloding of large plain areas along the rivers. Terrestrial vegetation that grows in the dry season dye as a consequence of the flooding and in this process causes oxygen depletion that can cause fish kills. Linked to the process of expansion and retraction of water on the Pantanal plain, this peculiar phenomenon is locally known as “dequada or decoada”, a consequence of the decomposition of the flooded terrestrial vegetation that produces a large amount of organic matter which are food source for many fish species, called detritivorous or illiophagous. So, flood in the Pantanal has negative and positive impact on fish fauna in the Pantanal.

Dear Emiko,

Thanks for informing us about "dequada or decoada"

In the 1980's on Lake Mendota in Madison, Wisconsin there was a large Cisco (Coregonus artedii) fish kill because of abnormally sustained high summer temperatures and drought. Cisco prefer to be near the thermocline since they epolimnion temperatures are generally too high and stressful for them. It is suspected that the Cisco became overcrowded in the metalimnion and depleted this area of its oxygen, resulting in a massive fish kill. Interestingly, since this particular fish mainly feeds on zooplankton, Daphnia thrived and fed heavily on algae the next spring and summer leading to some of the clearest water seen on Lake Mendota since records had been kept (over one hundred years!)

Water clarity in Lake Mendota since 1900:responses to differing levels of nutrients and herbivory. Richard C. Lathrop, Stephen R. Carpenter, and Lars G. Rudstam

https://www.uwsp.edu/cnr-ap/UWEXLakes/Documents/programs/convention/2014/JohnLyons-ProjectedClimateChangeEffectsonCiscoinDeepWILakes.pdf

Hi Kibria,

In the 1980s Lake Victoria (East Africa) used to have fish kills--especially during the dry season which was caused by diurnal change in DO as a result of turnover where anoxic waters would upwell into surface waters. There are several articles chronicling these events. certainly eutrophication of the lake which emanated from various causes had a share to the problem. see for example http://link.springer.com/article/10.1007%2FBF00008448.

Fish kills are also known to occur in Lake Tanganyika, especially in the southern--Zambian waters. This again happens during the dry season and upwelling of deep anoxic waters to the surface is the culprit. Despite great depth of the lake, the southern and northern parts are relatively shallow. In Mpulungu (Zambia) mixing of the waters can go up to 200 m during the sourth easterly windy dry season. This phenomenon is called Chibamfula in Zambia. So upwelling of anoxic waters is the cause. These events are supposed to be diminishing in Lake Tanganyika as the lake is warming and becoming even more strongly stratified.

For Lake Kivu, it is methane gas which is causing the kills

Dear Nathan,

The species (the keystone species- Coregonus artedii) you refereed to will be impacted due to global warming (rise of temperature and drought etc) since the species prefer cold water and high temperature is lethal to the species. Also it appears that 30-70% lakes where the species live will be also affected due to warming. In the projected circumstances, what are the proposed/possible measures to reduce vulnerability of the species from climate change?  

Dear Ismael,

Many thanks for your discussion on upwelling/ Chibamfula, anoxic water and fish kills (Lates niloticus and Oreochromis niloticus)  in Lake Victoria and Lake Tanganyika .  

I am interested to know further about fish kills related to methane gas in Lake Kivu, do you have any reference or web links  for such fish kills, which would be useful!

The largest factor of water quality degradation in Lake Mendota is excessive amounts of phosphorous and subsequent frequent algal blooms. Many measures have been put in place to try and reduce phosphorous loading which include a ban on fertilizer that contains phosphorous for lawn care in the City of Madison, a rain garden program to try and lessen the amount of storm water entering the lake and a strict erosion control plan for construction sites around the city. Efforts to try and get homeowners around the city to remove, compost, or mow leaves before they enter the storm sewer has also been implemented. The main feeder to Lake Mendota is the Yahara River and its watershed is mostly agricultural fields. Much effort has been put in educating farmers about the importance of having vegetated buffer strips near the river banks, strip cropping, contour plowing and encouraging the planting of no-till crops.

Unfortunately, Cisco is not a heavily popular fish for anglers to catch and most are not even aware of their existence in the lake. Perch are an angler favorite and their populations, I have been told by anglers, are not what they once were on the lake either. Nearby, in Lake Wingra roughly half the Common Carp population was removed since they were suspected to be the main culprit in water quality degradation. The spring after their removal had seen much improvement in the water quality but areas where sunlight normally did not hit the bottom previously saw a dramatic increase in submerged macrophyte growth. These areas essentially became un-fishable. Lake Wingra had happy swimmers and angry fishermen! Water quality solutions are complex and unfortunately rarely make all stakeholders content. 

Recently, I hear that many tons of fish in Nile river kills due to waste water discharge and also high concentration of ammonia in river.

Dear Nathan,

It appears that nutrients, algal blooms, common carp are major threats. Yes awareness and education would be important 

Dear Fikrat,

Thanks for letting us that waste water discharge and high ammonia caused massive fish kills in Nile. Do you know when it happened, i.e date ?

Dear Kibria,

here is some information on the Kivu methane killing fish and sometimes people as it bubbles up from time to time http://articles.latimes.com/2008/may/23/world/fg-lake23.

I could not find a journal article about it but when I do I will come back to you. I know a team of Belgian researchers who have been working in the lake for some time now and I would guess that they have more information on this than I do.

Cheers!

Ishmael

Hi Kibria,

This may not be a chronicle past events of fish kills related to methane gas in Kivu, but surely will give you some insights. The authors are on Research Gate. They can provide more information I believe https://www.researchgate.net/publication/242713778_Modelling_the_reinjection_of_deep-water_after_methane_extraction_in_Lake_Kivu

Ishmael

Article Modelling the reinjection of deep-water after methane extrac...

Dear Ismael,

Both links are useful, thanks. Golam

Anoxy in the Sea of Galilee. Happens when due to upwelling of anoxic water  caused by prolonged winds blowing offshore and pushing surface water layer away from the coast. MB-Y

    Oxygen Depletion

Low levels of dissolved oxygen (DO) is a primary indicator of lakes’ and ponds’ water quality, and as such, it is also directly related to the health of that water’s ecological community. In fact, it is most often the #1 reason why fish kills occur.

Two winters ago there was a fish kill on a small backwater of the Wisconsin River near Wausau, Wisconsin. There are several dams located on the river and most sections are drawn down before the spring thaw to add capacity to most reservoir portions of the river. We believe the draw down occured too quickly for all the fish to find and escape through the one 18" culvert that drains/fills the backwater. If any of the fish survived in the little pockets and holes after the backwater was drained, many were likely taken out when the ice gave way above them. Several more culverts or a larger culvert likely would have saved the fish.

Thank you, Muhammad and Nathan, for your inputs., yes DO is one of the most important indicators of WQ and can cause fish kills. 

https://www.researchgate.net/publication/261216309_Global_fish_Kills_Causes_and_Consequences

Technical Report Global fish Kills: Causes and Consequences

Municipal waste water not treated, because of technical difficulties at the waste water treatment plant. It has happened a few times.

Hi

Article An Update on the Global Stressors and Constraints Affecting ...

see the link

Technical Report Environmentally Friendly Sustainable Aquaculture Farm in Rub...

It was wonderful comments i support all your comments. Influent waters of lake as well as the activities in the particular lake will decide the WQ of Lake. If domestic wastewater or Agricultural runoff water causes to reduce the DO levels in the lake water may causes the death of aquatic life. Agricultural runoff might having pesticide or fungicides also causes for the death of aquatic life. Sometimes presence of Zn compounds in the wastewater also causes the death of aquatic life. Zn will react with sulfur compounds may form Zinc Sulfide which is very toxic for aquatic life. PAHs, bi-phenols, PABs, and Methane gas production due to fermentation or other chemical reactions leads the death of aquatic life.

Dear Golam

I our country, most of fish dead for cause on temperature shock from industrial region.

-Best

Water pollution is an important cause in killing fish.

yes I agreed !! and this is the high time to work on these aspects,

Excess phosphorus in Missisquoi Bay of Lake Champlain (USA/Canada). But by an interesting mechanism: at mid day during peak algal blooms, there is so much photosynthesis that oxygen becomes supersaturated; so much carbon dioxide is removed that pH rises dramatically. The combination killed a lot of fish.

Online Environmental Education to Help Developing Countries

https://www.researchgate.net/project/Online-Environmental-Education-to-Help-Developing-Countries