tetras with ich

Question
i haue a 20 gal with 16 gal in it. 2" rainbow shark 1.5" albino rainbow shark 5 coara guppies 1 tequila sunrise guppy 2 1.25" black phantom tetras and a 3.5" electric blue crayfish. the crayfish had been the lone inhabitant for a year. during this time i paid little attention to my tank. no food, no water changes, no filter changes. decided to start it back up and finally learned the nitrogen cycle. cleaned up, got new fish, and cycled the tank. all toxins are zeroed out now. yet, the tetras have ich.

Answer
Hello. That is way too many fish for one tank! I would try to give some of them to friends or relatives. Ich can be caused by a number of things. If one of fish have died recently the fish will have a possibility of catching ich. Also if you introduce a new fish sometimes can stress the fish out leading to ich. And haveing to many fish in one tank can stress them out which leads to ich. Ich has a free-swimming stage in its life-cycle so the whole tank must be treated, not just the affected fish. Do not use a hospital tank for this reason. EITHER treat with salt at a .3% solution OR with medications containing Malachite Green, Formalin or Copper (examples: Rid-Ich (US), Protozin (UK)). Increase tank temperature to high 70's and if using a Malachite Green medication keep tank completely dark and covered over. Continue treatment until fish have been completely ich-free for at least 3 days, ideally 6 days. Vacuum the substrate thoroughly after treatment has finished to remove any remaining parasites in tank. I found the salt solution works best. I hope I helped. Good luck cureing the ich.
Corinna