About a week ago I had three rosy red minnows die. Now I still have a minnow and a catfish in a 10 gal. and they are both completely fine. I did daily water changes for three days to get rid of anything bad in the tank. And before any fish died I had treated them with a parasite medication because one seemed sick. I tried feeding my rosy red today for the first time since the death of the other fish and he wanted to eat the food. He sort of nervously darted close to the flake, and then quickly darted (in choppy motions) away. When he eventually did get a bite to eat he just spat it out. The catfish ate the pellet that I gave him in like 3 minutes though. My minnow seems very nervous. He is just hanging in the middle of the tank and like every 30 seconds he'll dart around in weird motions... Last week when my fish died I used test strips (I KNOW THAT THEY ARE CRAP) aand it said that the PH was really high and the water was really hard. Now I am out of test strips and I haven't touched the tank until now since the last water change on monday. Is my fish just nervous? Does he need another fish for company? Is he sick with a parasite? Or is it the water quality? If so how do I make the water softer?