oxygenator problem....2 much H2o??

[Crankbait]

I need some feedback. I purchased an oxygenator a while back and have had nothing but problems. The first one I got was a portable bait model and I had crazy bad effects with it….fish dying and all that. Guy told me I needed a larger model. So I upgraded. Now I’m just running it in a cooler converted livewell. It was to my understanding that you just turn it on and let it run. The first couple of times I used it when I placed a bass in the water she jumped out of that water like it was boiling hot. Now I’ve had bass thrash before but never like that. The bass that were in the livewell were jumping and thrashing like there was no oxygen in the water. The bass ended up dead. My water wasn’t even that hot. What I ended up doing was taking altronix timer chips and making my own timer. The box consisted off two timers. Timer a would come on every 30 minutes (or whatever I set it to). Timer a would trigger timer b (which was the one that actually ran the oxygenator) which would run for 3 minutes. So basically every 30 minutes my oxygenator would come on for 3 minutes. In looking back my bass seemed like the sustained burns! They were red and irritated around the fins gills and even mouth. I’ve been doing some looking and it seems that you can actually over oxygenate water?? I’m no scientist or fishery biologist so I’m looking for help and opinions about this oxygenator. Keeping my bass healthy and alive is important to me