Details: 29 gallon tank, 2 zebrafish & 2 tetra's. 4 plants (2 floating type). Sorry too late for a fishless cycle.

I got a filter with bacteria on it and put it in my filter and things are going a lot better. The problem i am having is that the 2 tetra's are staying at the bottom by the plants and i can't get them to come up and feed. It's been about 48 hours now without me seeing them feed. Are they depressed? they seem fine. Are they feeding off the plants? I am not putting much food in the tank because i am afraid of the levels getting really high.

ALSO one of the zebrafish is at the top of the tank possibly gasping for air. I do daily water changes (with water conditioner) and all the other fish seem fine. I even make sure the water is the same temperature as to not shock them. Is the zebrafish okay? He has been doing it for like 1 1/2 days so far. The other zebrafish plays with him sometimes and he goes away from the top for a bit. He also seems alive / active when i come close to the tank. He also isn't taking any food. Any way to fix this? Or is he okay?