Hi everyone! My boyfriend's friend has moved away and left me his fish. I was happy to take them, but want to make sure everything is going okay. First of all, it is a 35-40 gallon tank, and there is 9 fish. From my research (not 100% sure) it has 4 neon tetras, one siamese algae eater, and 4 barbs. Now, they weren't well taken care of but are still alive. We had to empty most of the the tank in order to move it. We are slowly filling it up, allowing the filter to filter the water as we go. There is a heater and an electric filter. I tested for nitrites, got 0, my pH is 7.0, and the ammonia test came slightly past zero. I added a few drops of the chemical that treats ammonia. I also added stress coat (following directions on bottle) because of the chlorine and etc in tap water. They seemed to be doing okay at first, but now one of the tetras is swimming frantically up and down the side of the tank. He didn't have the neon streak when I got him, he was mostly pale white, now he is becoming reddish/orange. The rest of the tetras seem to be doing okay. (I have heard tetras can't handle stress well, is this the case?) Just wanted some opinions on how I'm doing and to figure out what is wrong with my poor tetra. Also, should I change the rocks? Full of black gunk and old fish bones and skulls. Thanks!!