Ammonia produced by fish

[David Bush]

Can anyone tell me how much Ammonia is produced daily by fish (fresh water) on average (mg per kg of body weight)?

[Glenn Varley]

Depends on a number of variables. Ammonia is a byproduct of protein metabolism in the fish. If the fish eats a lot of protein and not all the amino acids are incorporated into new muscle then the excess nitrogen is excreted as ammonia. If a fish is not eating it will still produce a small ammount of ammonia as the breakdown product of proteins that it is using up eg metabolism of muscle proteins plus purines and pyrimidines. Sorry I don't have any exact data but it should be in a paper somewhere

[David Bush]

Thanks yes it is that exact data in a paper somewhere I am hoping to find, and many brains work better than one.

Glenn Varley said:

Depends on a number of variables. Ammonia is a byproduct of protein metabolism in the fish. If the fish eats a lot of protein and not all the amino acids are incorporated into new muscle then the excess nitrogen is excreted as ammonia. If a fish is not eating it will still produce a small ammount of ammonia as the breakdown product of proteins that it is using up eg metabolism of muscle proteins plus purines and pyrimidines. Sorry I don't have any exact data but it should be in a paper somewhere

[Stuart Whitney]

Hi Glen,
I use a rule of thumb based on a paper "SRAC Publication No. 453" for Barra feeding. 2.5% feed mass becomes TAN.

[Stuart Whitney]

Stuart Whitney said:

Hi David,
I use a rule of thumb based on a paper "SRAC Publication No. 453" for Barra feeding. 2.5% feed mass becomes TAN.

[Pierre Garsi]

In French trout (O.mykiss) freshwater farm we calculate 45 kg/day (total of solid and dissolved N) for 1000 kg feed.
Ammonia excretion depend fish species and size, water temperature, feed disgestibilty energy. European seabass (D.labrax) is between 250-300 mg/kg of BW /hour and for turbot (S.maximus) is 70 - 120 mg/kg/H !!

[Roy Palmer]

I sent this question to a USA email group I belong to and got these replies - hope this of help
From Angus McNiven ([e-mail])
The usual rule of thumb is 250 mg per kg body weight per day. Ammonia excretion depends on a range of factors such as species, fish size, feed quality, feeding rate and water temperature.

Another commonly used estimate is that 2-3% of standard feed (30-40% crude protein) consumed will be converted to ammonia.

From Scott Zimmerman ([e-mail])

I'm not a water quality specialist, but NH3 production is highly dependant on water temperatures, feed quality and availability. Generally speaking, higher water temps will increase a fish's metabolic rate (and Biological O2 Demand (BOD)). Water temperature is inversely related to availability of dissolved O2 (higher temps, less O2). Other water quality parameters (i.e., pH, N, P, Salinity, TAN) in some cases to a lesser degree, will also impact a fish's ability to produce NH3. Then you have open and closed system rearing environments which will play a role in a farms total output. Outside of the obvious, there are many factors at work which determine NH3 production.

Cheers Roy

[David Bush]

Excellent just what the doctor ordered thank you