Purging

[syazwan]

Hey Aquaponic Community, I have a question regarding purging. I have a commercial aquaculture system (recirculating aquaculture system) and an aquaponic system for my family.

Recently I have taken out few of my Tilapia from my aquaponic system for us to eat (without purging), what I notice is that the Tilapia don't have the muddy odd taste to them, while my aquaculture system we have to purge the Tilapia to get rid of the muddy odd taste (at least a week or so for the taste to disappear), does anybody know why aquaponic system don't need to purge the fish? Is it because of the less stocking of fish in the aquaponics system compare to the aquaculture system? What I have read is that, the taste of Tilapia is from algae in the water, if my memory serves me right I think it was the green and blue algae. So does that mean that these algae is not presence in the aquaponic system or of lower quantity?

I apologize for my English mistakes, grammar spelling etc.. I hope some of you guys can shed some light into this. I would like to hear what you guys might know, think about this. Thanks =D

[TCLynx]

I've never found purging to be necessary in any of the fish I've grown in Aquaponics (tilapia, channel catfish, bluegill)

I'm not sure if it is because of the better water quality (lower nitrates) in the aquaponics or less stress due to the way I keep them and how we harvest (only moments from netting to dead, cleaned and into the ice water.)  Or minimal algae.

I know there are certain algae and bacteria that can give an off flavor to fish as well as the time, stress, and handling between harvest and being ready for the table possibly causing some off flavors.

[syazwan]

Thank TCLynx. I agree with you, might be due to the water quality of aquaponic system compared to an aquaculture system. Might be aquaculture system has high nitrates and there is a chance that more bacteria and algae (that are found less in aquaponic system) that can cause this off flavor for the fish. Worth an investment to create an aquaculture farm to an aquaponic farm, not only we can grow fish without the need for purging but also plants as well. 

TCLynx said:

I've never found purging to be necessary in any of the fish I've grown in Aquaponics (tilapia, channel catfish, bluegill)

I'm not sure if it is because of the better water quality (lower nitrates) in the aquaponics or less stress due to the way I keep them and how we harvest (only moments from netting to dead, cleaned and into the ice water.)  Or minimal algae.

I know there are certain algae and bacteria that can give an off flavor to fish as well as the time, stress, and handling between harvest and being ready for the table possibly causing some off flavors.

[TCLynx]

Right, the whole thing about not needing to dispose of "waste" water while also growing more food with the same amount of water is a great benefit, for the environment and sustainability point of view at least.

[syazwan]

I agree. Thanks TCLynx

[Keith Rowan]

try skinning the fish from the aquaculture system..

i've read that it's the fat next to the skin that carries the "muddy" taste.. and the "reddish" meat will have the strongest flavor, many people remove it

[syazwan]

Skinning? which part will that be actually? Do you have documents or videos on how to skin it properly?

Keith Rowan said:

try skinning the fish from the aquaculture system..

i've read that it's the fat next to the skin that carries the "muddy" taste.. and the "reddish" meat will have the strongest flavor, many people remove it

[Keith Rowan]

i can't access youtube from work, but it's easy with a sharp fillet knife.. do not scale the fish..

after filleting, put the fish skin side down on your cutting board, hold near the tail, use the knife to cut through the flesh, but not the skin, then just run the knife down the fillet

[syazwan]

sounds complicated, I need to see this to then I know how to. heh. I will try to do some research on it, Thanks for the idea. but, if i was to skin it, so I will only be able to take the fillet out is it? I mean only the fillet is use for consumption?

Keith Rowan said:

i can't access youtube from work, but it's easy with a sharp fillet knife.. do not scale the fish..

after filleting, put the fish skin side down on your cutting board, hold near the tail, use the knife to cut through the flesh, but not the skin, then just run the knife down the fillet

[TCLynx]

You can also skin the fish without filleting it.  There is more meat than just the fillet but many people want a boneless fillet to make eating it easier.  But tilapia often are not all that big so fillets don't get you a whole lot of meat.

[syazwan]

Its going to be tough for me to only sell fillets here in Brunei, We Asian also like fish with bones also, I am not sure why, but mostly we buy our fish complete. haha. Might just purge the Tilapia in salt water for a week. 

TCLynx said:

You can also skin the fish without filleting it.  There is more meat than just the fillet but many people want a boneless fillet to make eating it easier.  But tilapia often are not all that big so fillets don't get you a whole lot of meat.

[TCLynx]

I never noticed any "off" flavors in any of the fish we grew in aquaponics including, tilapia, channel catfish or bluegill.  I think it is either just because of clean water or the fact that we net, kill, and clean the fish very quickly so they don't have time to stress out and taint their own flesh with stress chemicals.

[syazwan]

Yes, there is no 'off' flavors for me as well, these 'off' flavors are mostly present in my aquaculture system hence I have to purge them for a week in salt water. Just wondering why the 'off' flavors occur for aquaculture system. Might be due to the stress as well as the nutrients in the water. 

TCLynx said:

I never noticed any "off" flavors in any of the fish we grew in aquaponics including, tilapia, channel catfish or bluegill.  I think it is either just because of clean water or the fact that we net, kill, and clean the fish very quickly so they don't have time to stress out and taint their own flesh with stress chemicals.