عزيزي الدكتور صلاح المحترمالسلام عليكم ورحمة الله وبركاتهشكرا لتوجيه السؤال. أسأل، هل توجد لديكم إمكانية لقياس الأوكسجين المستهلك من قبل الأسماك؟ أنا أتذكر منذ السبعينيات هذا ماكان يعمل لتحديد الإجهاد.أقترح عليك أخذ رقم موبايلي من الدكتور أثير أو الدكتور نجم رجب والإتصال بي للتحدث عبر الفايبر أو الواتسآب فأنا أيضا مشتاق لسماع صوتك والإطمئنان على أحوالك. ودمت بخير.

فرحان ضمد محيسن

Cortisol and Glucose

Cortisol and glucose are two of the most common stress indicators. In spite of the extended use of these indicators and their acceptance, some inconsistencies have been reported in the results of several experimental studies, much of them associated to undefined and uncontrolled variables which may alter the response in secretion of cortisol and glucose into the bloodstream. Most of those factors are not considered as direct stressors but have an effect on the intensity of the response which makes them a source of error. Some of those factors are related to metabolic changes in the organisms as an adaptation or acclimation mechanism; other are extrinsic to the fishes; other sources of error are caused unconsciously by the researcher during manipulation or due to inadequate control of variables, and may lead to intrinsic changes.

استاذي العزيز والغالي دكتور فرحان.. كلماتك وتواصلك اليوم معي هي اجمل هدايا الرب في هذه الايام الشحيحة.. تأكد انه لا يمر يوم لا نذكرك فيه انا والزملاء الاعزاء .. ساتصل بك حتما فلا زالت كلماتك تمنحني روحا جديدة كلما خنقني الزمن.. دعائي المتواصل لكم بطول العمر والسلامة...

تلميذكم

صلاح

Dear professor Nirmala

Thank you so much for the helpful information.

Please accept my deep appreciation for your response.

Dear Dr. Khalida

Thank you very much for your answer. 

Looking forward for more participations from you.

With my best regards

It is also possible to use physical measurements in addition to blood chemistry.  Simple measures of condition (e.g., relative weight, Fulton's condition factor) can indicate stress in fishes.  Also, liver weight can be used to calculate a Hepatic-Somatic Index (HSI, often known by other names) which can also reveal stress responses in fish.  These physical measurements often indicate long-term stress response, whereas the blood chemistry measurements mentioned by previous respondents often indicate short-term stress response.  I've attached a few links that use HSI as a measure of stress response in various fishes.

http://link.springer.com/article/10.1007/s002449900510

http://www.sciencedirect.com/science/article/pii/0044848688900294

http://www.sciencedirect.com/science/article/pii/S016041200300059X

Dear Salah,

There is stress and stress. What kind of stressors are you or will you deal with ?

Dear Jason,

Thank you so much for this really helpful information.

Best regards

Dear Dr. Neil,

Stressors which I meant could be of different origins like adverse water quality, crowding, competition, feed deprivation among others.

Looking forward to know your suggestions about this issue.

With best wishes

We developed a flow- through method of examining cortisol in fish. 

Article A non-invasive assay for monitoring stress responses: A comp...

Hay múltiples respuestas, como cambios comporta-mentales, reflejo de huida, modificaciones del color y aumento en células club.

Just a guess, but in the salmon world we are worried about lactic acid levels concerning stress.

My colleagues and supervisors have developed a Welfare Index for salmon in Aquaculture. 

Dear Salah,

In order for us to give you relevant advice, I propose you describe your project, including tested species, weight, sex, field, semi-field or laboratory work, etc.

Be careful, cortisol measurement is very tricky.

Best regards,

Neil

It would also be help if one knew the context of this question? Is this wild fish caged fish studies, in aquarium? There are behavioral metrics that also can evaluated depending on the species and context.

Fully agree with Neil Wang and Jackson Gross. You need to tell us a little more about your intentions. Then we can help you. My working group is working on stress responses in fish and invertebrates, see our papers.

Try and be more specific. There is the need for us to know the species, its ecosystem or part of the water strata it occupies as well as the type of water body. Is it fresh water or brackish or marine? All these fairly affect fish stress responses and tolerance.

Dear colleagues,

Thanks for your appreciated responses. My group is planning to study the physiological status of the common carp Cyprinus carpio L. from 25-50 g weight. Fish are under culture conditions in floating cages inside a large river. Another group is reared in earthen ponds supplied with freshwater from different source. Feeding regimen, water quality and stocking density are also different. Fish from adjacent natural waters could be included as a control.

With best regards    SM Najim

Dear Salah,

Since you won't be working under controlled conditions, I think that measuring primary stress response indicators like cortisol won't be possible nor useful. Not possible because of the rapid surge of cortisol in the blood following the capture for sampling (increases in 3-5 minutes). Not useful because plasma cortisol is too sensitive to environmental conditions. Even secondary response like glycemia may be jeopardized by the stress induced by the capture (increases in 8-10 minutes).

I think you should rely on longer-term indicators that are not rapidly influenced by short-term stressors like handling. I don't have much idea about this. I'm not used to outdoor studies.

Ive worked with 4 species of carp in both tank and open water environments. Can you provide the goals of your research? Is this for fish culture? Invasive species control? Its unclear the purpose. Clearly it can be as simple as fish size, length and body condition, fin quality etc. or as complicated as gene expression.

Dear Dr. Wang,

Please accept my deep appreciation for your fruitful discussion and suggestions.

Looking forward for more participations from you and other colleagues.

With best regards     SM Najim

Thank you Dr. Gross for your interest in this issue.

The reason behind this project is the contradicted production data from different culture systems of the common carp. In addition, there are some arguments here about the profitability of extensive culture (restocking of some water bodies) with this species in comparison with intensive systems.

I hope my original question became clearer now.

With my best wishes     SM Najim