Backyard Aquaponics
A place to discuss aquaponics

I've been poking the interwebs and talking to some folks locally, and getting varied reports on the importance of growth inhibiting hormones in AP setups. Most of the info I find seems to be geared to ornamental and aquarium setups where frequent and voluminous water changes reduce the hormones so fish continue growth unabated.

But in our setups (well mine) we only top up typically, which could cause accumulation of inhibiting hormones. Does anyone know more specifics about these, particularly how they degrade apart from dilution by water change? Do they get metabolized in the grow bed? Photodegrade?

What species are we talking here?

Tilapia, and in general.

Wouldn't have a clue about Tilapia... but I have put a number of Murray cod in 600L of water and watched one individual out grow the rest about 3:1... was told by someone supposedly well educated in the field of aquaculture that this is a natural process... in the wild a batch of young fish will inhabit a snag, the largest will exude more of a certain hormone that inhibits the others from growing as fast, they soon relocate to another snag avoid being eaten by their larger sibling.

On the other hand Trout all seem to grow at a fairly even rate when confined to a fairly crowded fish tank in an aquaponics fish tank... and at the rate they grow, from fingerling to about 500-600gm fish (gutted & gilled) in only six months, I doubt there's any kind of hormone holding them back.

I know... most of the aquaculture sources I read (who I think would be most concerned with feed conversion) don't mention this at all but the aquaria folks are all over it. I'm not worried about maximizing my conversion necessarily, but do want to harvest fish and honestly I just enjoy learning the nuts and bolts.

I rear tilapia and I don't believe a word of it.. I got like 100+ fishes in a small area and most of them are between 2-3 pounds... after a yr and half and I only top up water.. I dont even clean my filters and only feed them once a day... and yet they grow very fast.. I honestly believe that the volume of the FT is what limits your fish growth.. together with water movements.. a reason y the younger fishes may grow slower is because they my be starved for food by the much bigger fishes and aren't able to fully eat their share.. once your water chemistry is good I.e amm nitrite and so on are low... everything will be ok..