Backyard Aquaponics
A place to discuss aquaponics

Yes, crowding also inhibits spawning. In the beginning Tom kept males and females together. When he and Paula wrote the manual I don't think they were hip to the idea of sex reversal and genetic all male production. Now, we accept that as common practice. I hand seperate all mine.

I was wondering why Alaska would be concerned with finfish since most species would never survive in the wild, but I am guessing it competes with the indigenous fishing industry??? Keeping the Tilapia strictly as a source of fertilizer and for my own consumption keeps me legal here I suppose. I just wouldn't want to say I have 500 Tilapia for ornamental purposes..... hehe.

Years ago I tried to challenge the Deputy Director at Fish and Game here in California (through several conversations) by tactfully pointing out some of the hypocracy and contradiction in anti-Tilapia policy. In Southern California commercial Tilapia production is allowed near the Salton Sea, but not in Northern California. However the southern farms are allowed to truck Tilpia live into Northern California. Now there's a real low risk operation! It's all politics. It got me as far as I could throw a lead bowling ball!! I think if I were to go commercial, I would have to leave the fish part of the equation alone, and just recycle my fish as a cheap source of fertilizer.

That's good to hear that not separating them is not just the lazy guy's (read DD's) option.

lol....I would venture to guess laziness plays a big part. It's a chore for sure!!! I'm considering not seperating the next batch..

I guess what worries me is that I live in an area known for pot growers. Everyone just assumes that if a guy is doing hydroponics and a greenhouse, he must be growing pot. So I'm sure I'll be checked out. And if some bored official comes snooping around looking for something to write up....

A bored official looking for pot is not going to recognize tilapia. Especially if your water is deep or dark or murky. If he asks about the fish, you say they're an ornamental cichlid with fascinating breeding habits, but that you're a little disappointed with their coloration. Cichlids as a group are very popular aquarium fish.

Alternatively...You could mix in just a few bright orange short-finned goldfish with the tilapia, and then complain that you must have gotten a dud batch of goldfish, and they're just not coloring up for the most part. (Fry/fingerling goldfish start out black/brown.) Spit fiercely in the corner and declare that you'll never buy from that supplier again! Or just claim that they are black goldfish. In all honesty, they look so much alike from the top that I when I was netting and sexing my tilapia, I also sexed my white goldfish and threw him in the male bucket. Then I couldn't figure out why I was short one goldfish!! Then I remembered that one of my males was just a bit fat...there he was!!

Hydroponics does have somewhat of a nefarious reputation. I was a narcotics officer up until 2001 here in our area. We looked more for excessive electric bills or utility bypassing to tip us off on a grow operation. The last big grow operation was taken down as a result of alert neighbors reporting suspicious activity. Turns out these guys were buying up homes located in new suburbs and just using the homes as a place to grow indoors. The fact that no furniture or daily living activity was observed tipped neighbors into reporting.

Once the greenhouse is up and running just go to the state police and report your grow operation. Better yet if there is (and there is) a narcotics task force or marijuana eradication unit in anchorage, report it directly to them. They will look at you a little sideways, but it will ward off suspicion.

I'm also figuring that I could get a bit of notoriety. I'm planning on selling produce at the local farmers market. And I like to talk about what I'm passionate about.... Lots of people from our church are planning on buying from us and others just want to see it when it is in operation. And I wouldn't be surprised if some reporter came by eventually...
I guess whenever people ask me what kind of fish I have, I'll just tell them "Goldfish and other ornamentals...." "Just feeder fish I bought from Walmart and Petco..."

.....Cichlids. Janet makes a good observation. The narc officer would have to know his (or her) Cichlids very very well to discern a Nile Tilapia from say.... a Butterkoferi Tilapia (which is a highly collectable ornamental cichlid), and even then, jurisdiction over illegal pot growing is wholly different from jurisdiction over F&G violations. I could tell you the code section for growing pot, but I couldn't tell you the code section for possesion of prohibited species!...lol

But I've been thinking about the heating system. I already have a natural gas heater I was planning to run as a backup but the more I think about it, the more I'm liking the idea of a water heater. No point in heating the air when the water is what I want to be warm. And a water tank and the grow beds are going to radiate enough heat to keep the air temperature well above freezing.

My experience running a wood-fired boiler tells me that I might even be able to use a batch-fired system. A firebox full of branches or cardboard (or other burnable trash) isn't going to raise the temperature of 5000 gallons very many degrees (1 BTU/lb/degree F) . A whole cord of wood (4' x 4' x8' burned at 100% efficiency would only add about 12MMBTU or 300degrees to the water. Therefore, a 2 cubic foot firebox would only add 1/64th of that or about 5F (at theoretical max efficiency -- a decent real world system would realistically be about 30% of that). I would think the fish could handle a 5 or even a 10 degree fluctuation of water temperature -- as long as it happened over at least a 2 hour period.

My point: keeping the temperature up in my fishtank and therefore the whole greenhouse might be as simple as burning a bag of trash every few days.

Insulate your tanks and you're golden! Don't forget a lid.

What do they call those high mass ones - something like mortar or block stoves? I saw a high mass stove made out of a steel drum filled with rocks and a regular pot bellied stove inside - burn it all up really quick and the rocks stay warm for hours after.

European Masonry Heaters. Way cool, those. I first saw one in Germany on a cool fall day. I sat on the built-in bench. Mmmmm. I didn't really appreciate what it was until years later.

I'm still having second thoughts about the inflatable swimming pool as a fish tank. The more I think about it, it seems like a square or rectangular tank would be more conveninent and space efficient. If I beefed up the walls of my greenhouse, I could slap some plywood on the inside and have three sides -- then I'd only need to build a short wall and I'd have a rectangular tank. A 12' x 20' tank would hold approximately as much water as an 18' circular one.... I guess I would feel vulnerable having a 5000 gallon water balloon in my greenhouse -- especially since it is uphill from my house -- and my youngest can be pretty agressive with a screwdriver....

Solids removal sounds like it would be the biggest issue. I could vacuum out the gunk every day or week -- or maybe month...

The other thought I had was that it might be nice to have two tanks rather than one -- it would be fairly easy to put a partition and have two equally sized tanks -- that would also make the tank(s) stronger.

But then I started thinking about partitions in the tank -- It might be interesting to try a rectangular tank with partitions of different size mesh. Somewhat like a creep feeder we used to have for our lambs -- mesh partitions with holes small enough that the fry could swim through but not the bigger fish. As I understand it, the adults are not canibalistic, only the older siblings. So with a little more thought, I might be able to design a self-sustaining system that would a self-regulating population of multiple generations of fish. (Perhaps even some other varieties too -- such as Oscars -- if any fry or stunted tilapia swam through the mesh into the Oscars' zone, they would be a tasty snack -- of course then the Oscars would all line up at the fence and say "wanna come over to my house for lunch?....")

You would save on space that's for sure. If you could reinforce the tank utilizing that ferrocement method, you could design a conical bottom and rounded corners to facilitate the drainage? Either way I'm glad to hear you rethink the rearing tank issue. How are those fish? Did you get the 70 gallon up and running?

Not yet. I guess I got overly generous with the silicone -- I have one fillet that was not completely dry yesterday.

I've been keeping tabs on the ammonia, nitrate, and nitrite in the 10 gal tank. I've been doing 30% or more water changes every night when I get home from work.

My for the 70 gal tank was to fill it with water and then move the filter I have on my 40 gallon tank to the 70 gal -- and then run it for a day without fish -- just in case I have ick or some other host dependent parasite in my 40 gal tank.

But that way I'd have a cycled filter on the new tank. I suppose I could buy a brand new filter and some of that biofilter kickstart bacteria....

Keeping the fish healthy (and watching them ) has taken time away from working on the system outside.

But I have been learning. My growbeds are definitely taking something out of the water in the 40 gal tank. Nitrites and Ammonia are 0 and nitrates are staying in the low 20 to 40 range even with fairly heavy feeding of 5 large goldfish 5 2" barbs and 4 2" pacus.