Backyard Aquaponics
A place to discuss aquaponics

Started with 30 tilapia and all has been fine for 4 months. In the last 2 weeks have lost about 8. Mostly smaller ones. Water test show good, Ph 8.2 water temp 65-75f. See system tread for more info.

You say water tests show good
So what is your
Ammonia
Nitrite
Nitrate

Have you had some chilly nights in those past two weeks? How big is the fish tank? Tilapia can really be weakened if the water temp drops below 53-55 F leaving them open to infections and much cooler than that and they sometimes die outright.

All 0's
Water low temp is 65f
250gal insulated IBC

Have you cut back on the feed Talipia won't be able to digest food very quicky at 65. I cut the food back by 60% compaired to what I feed at 85 dec.

Yes about half as much

Are you still losing fish? If so do the fish show any signs of stress before dying? When my fish show any signs of stress (any behavioral changes) I stop feeding and do a large water change and pump air into the tank. This info may come to late hopefully things got better.