Backyard Aquaponics
A place to discuss aquaponics

I have read that prawns can be used to consume/break down solid fish waste but have no idea to what extent they reduce the load on standard bio filters/nitrification tanks, are there any studies on the reduction of waste or release of nutrients into the system using them? Could prawns be the best thing since red worms are are they just something else that can go wrong?

Don't know about prawns, but the ghost shrimp in my turtle tank poop a lot too.

Search the forum for gammarus.....

I read the gammarus thread, while interesting it does not pertain at all to fresh water prawns which sell for a pretty penny on the open market and could be a valuable additional crop. Only other use I could think of for gammarus is fish food when their population reaches the saturation point.

If your intent is to "sell" the prawns... then I think you might need to dedicate tanks/raceways to their production... and feed them accordingly...

From my experience of those doing prawn farming... they foul the water pretty badly... and have a much higher ammonia production load... than people think...

I am aware that prawns produce their fair share of ammonia too, but ammonia is easier to break down then solids which tend to create blockages and anaerobic zones, looking for creative ways to reduce the load on the system and avoid the need for extra gravel washing. If they can reduce the volume of fish waste I would think that to be a huge advantage adding them to the system in a limited number. Only real problem I see is that unlike tilapia they don't reproduce in fresh water and would have to be restocked every so often.

Where are you going to introduce them... into the fish tank...

If so... you probably wont achieve "a huge advantage adding them to the system in a limited number"....

Because you'll end up with a very "limited number".... the fish will eat them...

Fish eat shrimp.....No way! There goes my plans LMAO no I was thinking of a settling tank with multiple strand vertical netting since prawns don't get alog too well and need their space, figure I they can break down a portion of the waste and I can supplement their diet a little, when market time comes place them in a separate purge tank for a few day just like I used to do with crawfish. Once fish waste is broken down into the lower volume shrimp waste run that through the media filtration where worms break it down even further into worm castings which the excess of will be extracted with a swirl filter, and last but not least any fine suspended solids that make it through all of that get the fine mesh filter box before reaching the DWC beds. That is how it is working out in my head anyway.
I would LOVE to get 100% mineral return to the system without having to run an extra aerated tank and without having to do constant maintenance on gravel, seems reduction of waste is critical to that.

Ahh.. OK... did similar in my blue barrel system... water drained (slow flow) into two interconnected settling tanks... with duckweed and yabbies...

Yabbies? Is that Aussie for crawfish or something? Sorry never had a chance to visit yet, don't speak the language.

I think you'd benefit from a little different approach. Solids removal is actually relatively easy to accomplish mechanically and in an extremely efficient manner, as long as the system is designed with the removal in mind, and the correct equipment is used to accomplish the task. Don't rely on media beds to trap (note I said trap, not remove) solids. Just because they "disappear" into your beds doesn't mean they're gone.

With proper solids removal, the ammonia load with a system is quite predictable. With a lack of proper solids removal, ammonia spikes and a host of other water chemistry swings/spikes/issues are so likely that, in practice, they are essentially a certainty.

But if you simply remove all solids from the system don't you have have to rely on mineral supplement since you are in effect simply removing them from the system continuously? From what I understand worms do a good (though limited) job at releasing the minerals back into the system.

Nup. Its aussie for yabbies.



Yea, the english language can be a little difficult for some lol

You can always dose back the nutrients contained in the solids. Removing them provides you a vastly improved level of control, making it possible to keep things far more stable and consistent.

Yeah I heard English is tough, some say it is pretty similar to American but I don't think so
I lived overseas for several years, and have heard just about every variant of English there is but yabbies is a new one on me.