My 40 breeder tank was really doing well with three CA cichlids and 6 panda corys and I had to go and screw things up by adding 5 zebra danios. I thought they would add to the tank but all they do is eat the blood worms and other frozen foods that I feed to my fish. The Danios are very fast, very bold, and pretty much take over the top of the tank so they grab all the food before the other fish have a chance. I have had the danios for two weeks and they ALL look pregnant because they eat so well. I tried moving them to my other tank but they were too aggressive with my endlers. I wish I had never bought them and I don't have the heart to flush them.