What's Wrong With My Tank?
I don't know what's going on with my tank. For one thing, one of my female guppies is looking weird, skinny with reddish gills. (I previously posted on this thread under "Skinny Guppy.") Now I have had 2 julii corys and 2 neon tetras die. The two julii corys seemed to have slightly reddish gills. One was a newer addition, about 3 weeks in the tank. He was smaller, maybe about 3\4 of an inch. The other cory we had had since December, and he was about an inch and 1\2. It may be important to note we recently changed light bulbs, and the new bulb makes everything in the tank look a more reddish hue, so I am not 100% sure the color in the gills had changed, or if they just look more red to me. We also had 2 out of 6 neon tetras die that were added at the same time as the little cory. These had no noticable symptoms, nothing on the bodies, no injuries that I could see.
I was worried about ammonia so we tested, and it was somewhere between 0 and .25ppm. We did a 30% water change right away, and about a week later we did another 10%. Ammonia is still testing near .25ppm. I did some reading, and found that some people were having innacurate readings with the API ammonia test. I'm not sure what to think about that. This testing kit was so highly recommended! My tap water tests the same as the tank water for ammonia, but we treat it before adding it to the tank. Nitrites are 0, Nitrates are 20ppm.
I have been reading up on diseases and parasites, but I can't say I feel confident about trying to diagnose the problem here. I see no signs of disease, other than the possible reddish gills. I don't want to just start guessing and dosing my tank with anything. Even if we get a better ammonia test and find our ammonia really is close to .25ppm, I am not sure what I should add. We recently added a new sponge filter, so hopefully, that will help soon.
Any ideas or advice here? I am so reluctant to mess with things and make it worse. I need help. I don't want to lose more of my babies. Please let me know if you have any ideas for me. Thanks, fellow aquariasts!