I am currently working in river monitoring program and have been using a combination of biochemical indices histopathological biomarkers of exposure to choose according to need, in order to link the presence of compounds with significant effects on tissues such as gills and liver

Not very sure about what do you mean. Toxicity of biochemical markers is zero, they are not toxic because they are part of the fish system.

Hi.

I'm not sure about what you mean by "toxicity of biochemical markers". I suppose you meant to ask for the meaning and perhaps types of biochemical markers that you can evaluate in freshwater fish in addition to the histomorphology that you can currently using.

Briefly, as I assume that you know, biomarkers are biological responses or changes that are brought about as a result of exposure or effect of pollutants or stressors.

In your study, you are probably carrying out a risk assessment of freshwater fishes in the wild using these biomarkers or you are exposing some freshwater fishes in the lab to some toxicants (at either acute or sublethal concentrations).

Hence, some common biochemical markers you can evaluate are antioxidant enzymes (superoxide dismutase (SOD), reduced gluthathione (GSH), gluthathione-s-transferase (GST), catalase (CAT)), liver function enzymes (glutamate oxaloacetate transaminase (GOT) aspartate transaminase (AST), glutamate pyruvate transaminase (GPT), alanine transaminase (ALT) amongst others.

If you need the protocols or references for these procedures, please let me know so I can send some papers to you.

Hope you find this answer useful.

Regards.

Hi Rodrigo,

Some biomarkers can be used to link changes to certain types of compounds exposure and/or effect, but generally they are not compound specific. Nevertheless you can narrow your search of the potential "culprit" for the observed effects in the exposed fish. For example, some proteins (Besides those that Temitope Sogbanmu mention) like vitellogenin are considered a biomarker of effect caused by estrogenic compounds (in males fish), or metallothionein proteins family that binds to some metals (perhaps you may used as biomarker of exposure). You can look the literature to find changes that you may able to find at histological levels, like undifferentiated gonads in adults, necrosis, apoptosis, etc..

I hope this helps, best.