Massive die in 60gallon

[ZHiTcH41]

5 boesemani rainbows. 8 guppies. 2 dwarf puffers. 3 Siamese algae eaters. 1 red rAinbow.

I feed my fish some black worms yesterday evening and a few hours later the fish were swimming at the surface of the water. I did a 30% water change. Didn't help, I have an air stone and two filters that fall onto the surface of the water. So I know lack of oxygen isn't it. I also have live plants.

I feel it has to be the black worms. Does anyone have an idea what it could be?

Here is my tank

 

[sillygirl423]

What are the parameters of the tank? (Ammo/nirtrite/nitrate) is it possible something has gotten into the water?

 

[LyndaB]

I once fed brine shrimp that were moldy. I didn't have any deaths but had to do multiple water changes to clean it out of the tank.