Since we live in the Arizona desert, which is a hot climate, the best edible fish for us to use in an aquaponics system it tilapia. Nile tilapia, in particular, can handle warmer temperatures. This post will be dynamic – the more we learn, the more we’ll add.
Tilapia are fast breeding (up to 1500 fry/spawn) and fast growing (from six to nine months to eating size). Males grow faster than females, so commercial producers use methods to ensure all male reproduction, or to convert females to males. We home-growers don’t need to be concerned about that, though.
Tilapia are cichlids, cousins to the pet-shop ciclids, like the oscars. They are aggressive and not-so-friendly fish. Tilapia are omnivores, eating both meat and veggies. For the most part they’re herbivores, but will eat their young and other proteins. As scavengers, they like to eat dead stuff, like dead fish and fish food. They enjoy algae and water plants like duckweed.
As we’ve been working to building our breeding colony, which is a male and a handful of females, we learned that some tilapia are more aggressive than others. They can be brutal, attacking each other, biting each other, and stressing each other to the point of death. In general, they fight for power and territory.
We currently have three females, around 4″ in length, that we’ve been able to sex once we figured that part out. One is a evil fish, and is being kept in solitary confinement because she has no social graces at all. The other two aren’t particularly friends; the larger one keeps the smaller one confined, but they aren’t actively fighting.
We also have around 70 others who are fry and small fingerlings. They are all in a 15 gallon tank and doing fine. What we’ve learned is that tilapia get along better in aquarium environments when they’re crowded; they can’t pick on just one so the aggression gets distributed, or just mellows out. We’ll soon be putting the largest four of these in with the two nicer females in hopes of 1.: crowding them a bit, and 2.: finding a male. These four are small enough to be difficult to sex, though we have our suspicions.
A breeding colony, as mentioned, is one male and three to five females. With females around, the male will build a nest and protect it, even against his harem. So he needs a visual barrier between him and the females. A flower pot does well for this, so I hear. We’ll let you know once we find our male.
The reason a harem is needed is because tilapia, like rabbits and chickens, will literally kill a single mate with sex. The male is quite aggressive with his desires, and giving him multiple females allows the girls to get breaks and recover.
We currently have a 29 gallon tank that will serve as our fingerling tank, and we have a 15 gallon for our fry. A little 4 gallon tank serves as an infirmary for sick fish. And of course, the 300 gallon main tank or “pond” will be the food tank. But for breeding, we’re using another 29 gallon tank. This seems crowded, but our fish aren’t too large yet, and too much room isn’t a good thing, as mentioned above. We could put the breeders in the pond, but we want to control the conditions more. Our PH is very high here, and lowering PH in a small tank is much easier than controlling it in a large tank. We’ll see how that goes!
Types of Tilapia
There are a three main types of tilapia that are used for food. Nile Tilapia (O. niloticus” reddish to white with bars on caudal fins and white color strips on dorsal and anal fin); Blue Tilapia (O. aureus: bluish in color with red margins on fins); and Mosambique Tilapia (O. mossambicus: dark in color with no bars on fins). There are many hybrids. A popular hybrid is the Red Tilapia.
The main differences in the species are relatively minor. The age to maturity and aggressiveness aren’t significant enough to worry about in a home system, but the PH tolerance and temperature tolerance might be. You want to raise the fish that fit your environment best.