I've gone and done something really dumb. I used the same supplies on all four of my fish to do water changes. A week ago my boy Katniss was swimming on his side, struggling to breathe, and overall suffering. I ended up putting him down because no one could identify what exactly was wrong with him, and he was obviously in a great deal of pain.
I feed my fish four pellets a day. I do biweekly water changes. Two are in 1gals and one is in a 2.5gal. (College tank size restrictions) I tested the water chemistry this morning... perfect across the board. I've been doing 50-75% water changes and API salt treatments for the past 8 days to help their fins grow because they're all biters.
I woke up this morning to an inexplicable death. I have a video here, second one down, of him just last night, 8PM PST: http://bettabeblissful.tumblr.com/
... this is the same fish that was dead this morning. No spikes, no strange anything.
Now onto Calvin. Calvin has been sitting on his head all day in a corner of his tank. He is emaciated, weak, and swimming slightly funny. It looks like he has the beginning of what Katniss had. The only thing I can identify that's strange on his body are red streaks in his tail, but I thought that might have been ammonia burning from his slow transition from college back to my house. Again, there's a video of him last night near the end of my blog, acting perfectly normal.
Harlot, on the other hand, I can't tell if he has streaks or not because he's a red fish! But he too is just sitting in a corner of his tank, weak, not moving, on his side.
PLEASE, someone help me. What is going on and what can I do IMMEDIATELY to save my remaining fish? Petco closes at 9!