Hello,

I have a one year old 1/4 acre pond that was initially stocked with fathead minnows and hybrid bluegill in August of 2021. I then stocked it with shiners and 35 hybrid stripers in late November. The pond has two aerators running 24/7, and the water has been crystal clear after a month or so since the pond was built. Everything has been doing great with virtually no dead fish observed. I have pellet fed occasionally, but certainly not consistently. The fish have done well and grown substantially. The hybrid stripers were about 3" when stocked, and now they are about 8 inches long 7 months later. Yesterday morning I added 15 lbs of fathead minnows since I was no longer seeing schools of minnows as before, and this evening I had 4 hybrid stripers nearing death. This is the first time I have seen any dying fish in the pond. My initial thought is that it could not be coincidental that I suddenly have dying fish on the day I loaded the pond with minnows after 7 months of doing nothing but tossing pellets a few times a week. Does anyone have any idea what may be going on?

Thanks,

Leo

My initial thought is this is a coincidence... HSB are prone to a tighter tolerance of water parameters than many species. They are very intolerant of low DO. If it's not angling stress, I'd have to say it's a water quality issue.
What's current water temp?
Maybe shutting aeration down about 8am and leave it off during daytime, start again about an hour or 2 after dark in the Hot times during summer. possible heat stress.

If you know, did those (4) HSB end up dying?

Leo, in your shoes I'd take Snipe's advice and check water temps. If there is no thermal refuge available, HSB may suffer from stress due to extreme high temps like we've experienced lately.

If (4) of the (35) HSB were affected, and perhaps died, it's 11.4% of the HSB population which does, I think, point to a system level issue.

So I think Snipe is on target too.

Your water is too hot. Hybrid stripers can't tolerate too much heat. Do as Snipe suggests, put your aeration system on a timer. I'd suggest 9:00 pm to 9:00 am.

Bob:

How much cooler is the water when the system only runs from 9P to 9A vs 24/7?