Backyard Aquaponics
A place to discuss aquaponics

I have a 1500ltr fishtank with 2 BYAP grow beds. I have successfully had 20 silver perch that I have now harvested.
Two weeks ago I put in 22 barra fingerlings, aprox. 75mm. In the first week 2 died. I expected this to happen. All was well for a week and a half, until yesterday I had 10 dead, this morning all the others were dead. They had grown to approx. 150mm and seemed well and sprightly.
Every dead barra had its mouth and gills wide open.

Water readings are as follows

nitrate 0
nitrite 0
ammonia .25ppm
Ph 6.6

water temp 20deg C

Can anyone shed any light as to what may have caused this?

Thanks.

temp?

temp is 20 deg c

Sorry to hear of your loss.

Wouldn't this suggest a low dissolved oxygen issue????

Were they gulping at the surface before carking it?

Do you have an aerator in the fish tank?

Fish can have flared gills for quite a few reasons. This is reasonably interesting http://www3.sympatico.ca/drosera1/fish/illness.htm

I would have thought 20 deg is at the low end of the scale for barra, they may have been stressed. When did you measure the temp? What was the temp overnight is what I'm getting at.

Id suggest Temp and or low DO, 20 is right at the low range for Barra, I've had them lower but water has to be incredibly clean not just in the chemistry but when temp gets low and there metabolism slows they can't handle any fine particules in the water
I found the trick with small Barra is heaps, heaps of air and lots of salt at times when my guys were small salt levels got as high as 12ppt plus I never feed at under 22c