I have a 25g tank with a 30g filter that has been running for about a year and a half. Currently there's 2 kuhli loaches, 4 peppered cories, a siamese algae eater, and a zipper loach. They've been in there since my tank has been cycled and I've haven't had a problem. Lately I haven't been seeing my zipper loach, he usually hangs out at the front of the tank. So I was feeding my fish and he comes out and he is SO skinny now. He's literally like bone and scale and I don't understand why. I wish I could get a picture but like I said he doesn't hang out where I can see him. I hope someone can shed some light on this because I really don't know. None of my fish are aggressive toward each other, I've never observed any chasing or biting or anything. Please help! I don't want him to die.
ps. all water parameters are good.
ps. all water parameters are good.