I've got feeder guppies in there as well as rosey reds and some catfish. Sometimes they eat my danios too though but I expect them too. Every couple of days I put them in a separate tank and feed them reptomin and veggies for more nutrition. I also have a cuttle bone on the tank that they sometimes crunch on for calcium. They're in a 75 gal tank with a Fluval FX5.