Siamese Algae Eater Has Lost a Lot of Weight
I bought 3 SAE 3 week ago from my LFS and am having trouble diagnosing an issue. My tank is 2 years old, with injected CO2 introduced 5 months ago. In the middle of the day, my ph is 6.8 and KH is 5, so I think my CO2 levels are ok. There's guppies, angelfish, and shrimp in the tank right now and they all seem fine.
One SAE died the first day, maybe from stress and transportation. The second has thrived and is much bigger than when I first got it. The last one has lost weight and seems emaciated. It's actually shrunken and looks really skinny. I don't see any other signs of disease on its body. It swims around a little more slowly, but still eats a little. Both remaining SAE ignore my fresh veggies and veggie wafers, so I'm guessing they're surviving off algae.
Any ideas what's wrong?