Dear all,
I am new to the world of Artemia and I am running into some troubles I hope someone might be able to help with :) I grow A. franciscana nauplii in the lab (starting salinity : 45g.l) in glass tanks, at 23 degrees C and feed them with dry spirulina (1g diluted in 200 ml of RO water, and then I dispense ~1-2 drops of this solution per individual). I use Red Sea Salt diluted in RO water but I do not proceeded at any water change between the moment they are naupli instar 1 and to the moment they form pairs. I incrementally increase the salinity by 5% every other day when the larvae are 10 days old to reach a salinity of 90g/l. I noticed from the literature that my Artemia are growing slowly: ~4weeks to reach adulthood. Not sure why, could be density, but this is not my biggest issue. See below...
When pairs form in the tanks, I isolate them into individual containers (so far, I have tried plastic cups, plastic drosophila vials, and glass beakers) in a volume of 150 ml of freshly made 90g/l salt water, give the pairs a drop of food. Within 48-72 hours, all of these isolated pairs die whereas those in the main tank, at the same salinity, with the same diet, exposed to the same photoperiod regime and the same air, are just fine. Does any one have any idea as to why the isolated pairs die when the others are fine?
Worth noting: in the isolated pairs, males develop very quickly some black spots on their legs are claspers. I do not know what this is, I can't really find any info on this potential (?) issue, but suggestions on what that might be are welcome :)
Many thanks in advance for your help and your time
Clementine
1)
The reason for the slow growth of Artemia is that you changed the salinity steadily by 5ppt daily, even when they are in the growing stage - which stunts growth/takes quite a long time to reach adulthood. Do not increase salinity from that of seawater, uptill 15-17 days, by which time the young ones will easily reach adulthood.
Only then increase the salinity daily by 5ppt/day upto the required level you want.
2)
Artemia cannot withstand any physical shock like pouring it from one container to another. If you do this, they will all die in a short time.
In case you want to transfer, do it by using a fine brush - lifting it from one container & immediately placing them in another.
Artemia cannot ( Except the newly hatched naupli) cannot withstand any aeration, as if done in case of adults, they will die after a time.
Dear Chandravadan Trivedi and Ahmed Farouk Basuony Abdelhamid, many thanks for answering my questions and your precious tips :) Your help is very much appreciated.
To Chandravadan Trivedi: about your second point: if I have to change the water of thousands of individuals, taking them one by one with a paint brush will take me for ever! :) Do you think the use of a fine mesh net (such as those used in shops to catch fish in tanks) will be okay to transfer my Artemia into clean water? I also use a large plastic pipet to transfer individuals from the tanks to individual cups but I will be extra careful to make the transfer as gentle as possible.
Thanks again !
If you want to change large quantities of water from an Artemia tank, then keep the Artemia within the tank & physically change water & then add water slowly through the sides, so as not to physically disturb the animals.
Two methods are available to you.
1) You can use a source of an undiffused pinpoint light to be pointed at one corner, preferably the bottom one so that a great part of the animals will congregate there & with a siphon, remove water from the opposite diagonal top corner, preferably from surface onwards.
2) You can immerse 90% of a box-shaped mosquito net from the top,keeping 10% above water level & slowly remove water from the tank with the help of a siphon. Care should be taken to see that no animals from outside get stuck on the net, if this happens, all those stuck ones will die. Hence the siphon end within the mosquito net box is kept exactly in the center of it so that the sucking of water is equal from all sides.
Using the fish net for transfer is never advisable. Using a brush is for transferring a few ones only.
Optimum salinity around 36 psu is reqd., but NH3 and DO level to be considered
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