How to create a realistic fish?

Hi, I want to create a game with blender and unity and i wanto to create a lot of fishes.
Can you explain me how to do fishes like these :

Thank you very much.

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Moved from Tutorials, Tips and Tricks
reason: it is a support request

the A and O are the textures and maps. maybe you can find some on cgtextures or any stock,
create a very sattle normal map with gimp or ps or any tool you prefer, then create a specular map where you can define the parts where the material shoud be glossy and where not. since a Fish is rater glossy, the specmap should be mostly white.
the model ,in my opinion, is ok so far. maybe a bit ajustment in the face/mouth.

me personally would use less polys on the body, and more increase the resolution in parts that defines the sillhouette…

you could also have several materials which might help with the UV maps !

happy bl