It’s been seven weeks since we received our small fingerling Tilapia and they are still growing like weeds. Back then they could fit in a small plastic bag, but now they are too big for a 55-gallon aquarium.
It’s all too obvious that the tank is not big enough, because our Fluval 306 canister filter cannot keep up with all of the effluent, even though it is designed to clean a 70-gallon tank. We are now considering a Fluval FX-5 canister filter, which is rated to handle up to 400-gallon aquariums. Apparently the number of gallons is not as important as the number and size of fish in the tank.
Two days ago, I noticed that there was a “dent” in the gravel in the front-right corner of the tank. Initially, I thought the gravel had been moved during a water change, but then yesterday I saw one of the tilapia repeatedly picking up gravel with its mouth, one or two pieces at a time, and dropping it a few inches away. Eventually the “dent” began to look similar to a bird’s nest and two tilapia were guarding the area, chasing away any intruders.
When there was no one to chase, one of the tilapia would often wag its tail in the face and on the side of its partner, as the partner ignored all of the effort expended by the other.
They also performed a dance, spinning around each other as they hovered over the nest.
I estimate that they were about four weeks old when we received them, so they are about 11 weeks old now. Various sources indicate that White Nile Tilapia are sexually mature at 4.5 to 5 months of age, so we still have about eight to ten weeks to wait before they can reproduce. Of course, if my estimate is off by a couple of months, we may have some babies swimming around very soon.