How To Take Good Pictures Of A Fish Tank?

[Ninjouzata]

I just follow the fish around (like stated above) and take tons of pictures and delete the blurry ones. They slow down or sit still eventually..patience

 
I don't use flash unless it's lights out and the fish is in a good position that I just have to take a pic, or for my betta who likes to come to the front and the only way to make him not look black is using flash.
 
My pics aren't all that good, especially compared to others on here, but I hope it helps? D:

 

[AeonMapa]

It depends on the fish really. I find some fish look spectacular with sunlight hitting them, others do better in darker situations. Many fish show best colors under certain lighting and some colors are only seen when lit properly. Other fish like Oscars, severums, red devils etc. Have some very solid colors that can be seen under most any light. Find the lighting that compliments your fish best first. Also I find that fish show best colors when being fed live food. You'll want them to
look their best in the pictures so condition them to look good

Next you need a camera with a decent shutter speed. Fish move very fast without warning and are sometimes always on the move. Cichlids and catfish stay in place long enough to get shots but others are not so easy. Environment can help. A betta given a thicket of floating plants will rest among them from time to time. Observe when the fish stops moving (chewing food, resting)and try to anticipate.