Backyard Aquaponics
A place to discuss aquaponics

Hello all,


So, after more time than I expected my water chemistry is finally starting to sort itself out. My ammonia levels are dropping, NO2 is starting to spike and NO3 is starting to show itself. At this point I'm feeling optimistic that the system will be ready for fish in the next week or so. I'm planning to add about 100 2" Channel Catfish to the system.

I have a 300 gallon FT and three 24 Square ft. grow beds. two of these are DWC and one is full of gravel with a continuous flow just below the surface of the gravel. I've started seedlings in all of them and everything is coming up nicely.

I had intended to cycle the system without any fish and I started that process by adding ammonia up to 2ppm. The problem that I was having was that I started getting a huge mosquito larvae population growing in all of the tanks. I sort of panicked and went to the local aquarium store and bought 20 "feeder fish" to help tackle the problem. That seemed to do the trick and the larvae problem quickly went away.

I had other issues as well such as a massive algae bloom which apparently was sucking up all of the ammonia. For a while I was under the mistaken conclusion that my system was "cycled" since the ammonia kept dropping (and I kept adding more). I now think that the algae was eating it. I never had any NO2 or NO3 readings until recently. Throughout this whole process I lost exactly half of my goldfish. there are still ten left and they seem happy and healthy even with the ammonia and nitrite levels being up there.

So, given that brief history, here are my questions:

1 - Will 100 fingerlings overwhelm the biofilter? I'm hoping that the fact that I've kept the ammonia up to 2ppm throughout the cycling process will have prepared the system for that level of stocking. Obviously, I'll have to monitor things closely.

2 - Is there any reason to take out the goldfish? They seem happy now but I don't know how gold fish and catfish get along.

Thanks for any insight that any of you might have.

Scott

I'd expect 100 catfish to be too much, too many, for a 300 gal Fish Tank (and how much volume for the growbeds?) Do you have any other filtration or just the growbeds?
My Magic 8-ball says "Catfish love goldfish."

--
Sam

I have to agree, I think 100 is too many for a 300 gallon tank but how many you can have depends on the amount and type of filtration you have and the size of the tank as well as your intended grow out size. Based on 1 lb grow out size with 180 gallons (roughly) of filtration probably 36 is the maximum and I'll suggest about 20 till you get the hang of it.

http://www.backyardaquaponics.com/forum/viewtopic.php?f=12&t=6646

This has a bit of information from TCLynx who grows them in Florida - http://blog.brightagrotech.com/catfish-in-aquaponics/

She mentions a couple of things 10 gallons of tank per fish and that 300 gallons is the minimum tank size she would use.

Thanks guys,

I have a 55 gallon settling tank and a couple of 5 gallon buckets with expanded clay in them for filtration. I know that I need to work on this a bit more but I was hoping between that and the first grow bed being a media bed, I'd be ok for a while since the fish will be small at first.

The grow beds have a volume of about 180 gallons each and all told I have about 900 gallons in the system.

Let me ask you this: does it make sense to figure on just culling out some of the fish as they grow? In other words, I may harvest some of the fish long before they reach 1lb. if the conditions become undesirable for the fish. The main reason that I'm thinking of putting 100 fish in is that the company that I'm buying them from has a $200 minimum order before shipping and the fingerlings are $2 ea. I could of course get fewer fish for $200 but that seems like a waste.

If the catfish eat the goldfish, well, that's what you get for being a "feeder fish" I guess. all in all they probably lived a longer life in my system than they would have at the aquarium store.

[quote="scotty435"]I have to agree, I think 100 is too many for a 300 gallon tank but how many you can have depends on the amount and type of filtration you have and the size of the tank as well as your intended grow out size. Based on 1 lb grow out size with 180 gallons (roughly) of filtration probably 36 is the maximum and I'll suggest about 20 till you get the hang of it.

http://www.backyardaquaponics.com/forum/viewtopic.php?f=12&t=6646

Hey Scotty,

Thanks for calling this thread to my attention. There's definitely some good information here. I agree. I think 100 is probably too many.

Thanks.