whats wrong with my fish ???!!!

[gooftroup09]

ok so i have a water cow (eleotris picta) and an oscar. they are both a little less than 5". yesterday they were fighting extremely bad. They ripped off fish and missing scales. not pretty. So i moved the water cow in a 10 gallon that i had laying around. I add half of his tank water and half new water. about the same temperature. i have a sponge filter that i put in it. it looks like it was helping but i took the gravel out because the waste is just inthe gravel which was making the ammonia rise (i think) and he was gulping for air and sitting over the sponge filter as if it were no oxygen in the tank at all, so i removed the gravel. The water got super cloudy so i did a water change and added more of his old tank water (next day) The water is still cloudy. and his is still swimming all around the tank and sitting near the top. what else can i do!!! did i do anything wrong?? Becuase in the old tank he just laid at the bottom and waited for food to come past..no he is overly active