thats not completely true. minimum is a 30 gallon long. once they reach about 7-8 inches, they grow slower. i think they will grow that big in 3-4 months if your bichir is 2-3 inches right now
I know that you didn't know that this fish was going to grow this big when you bought it but don't rely on people to take them off your hands as nobody may want it!
P.senegalus maximum size 12''
A normal senegal grows an inch to an inch and a half per month till 7-8 inches then growth slows
bare minimum for 1 adult senegal would be a 30 gallon tank 36x12x16 -Anne