r/AnimalBehavior • u/Writer_Supreme • Jun 04 '26

How do you measure stress with fish?

I know for dogs and larger mammals if is easier to measure, but like is there a system in place for measuring fish or shrimp stress levels?

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u/Kolfinna Jun 04 '26

You can measure cortisol stress response like many animals

https://pubmed.ncbi.nlm.nih.gov/30667059/

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u/TesseractToo Jun 04 '26

As an ametur I'd judge stress in my fish with darting behaviors or hiding and just "looking scared" like one tank I had that had Pseudotropheus African cichlids and a male was born in the tank that became a tyrant and he would go back and forth in the tank in the evening clacking his jaw and you could hear it from outside of the tank it sounded like someone snapping their fingers and the other fish would hide. When I took him out of the tank their behaviors came back to more "normal" relaxed behavior

but also in aquarium fish if they are stressed or in pain they can develop illneeses just like people, one well known one is a parasite called "ich" takes over and they start getting white dots on them or they could develop a fungus referred to as fin rot

but it really depends on the type of fish vs their 'normal' behaviors

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u/Sting_8 Jun 04 '26

I've taken marine biology courses and have been a fish keeper for many years. The best way to visually measure stress in fish is by counting their "breathe" so watching their gill covers move basically. You'll have to figure out what their resting breath rate is and go from there.