I have a 7 year old hybrid tilapia. He is the result of a research experiment done a long time ago. All fish in the tank the fry he was raised from were hybrids. It is probable that he is a 4 species hybrid, but I will never know. We thought all the fish in the tank were male. The adults in the tank he was spawned in were: Oreochromis mossambicus x O. hornorum and O. nilotics x O. aureus If he is a result of 2 identical hybrids spawning or two different hybrids spawning is a guess only a DNA blood test could answer. For now, presume he is a 4 species hybrid. My question is how big should I realistically expect him to get? He was moved into a 125 gallon tank last year at 14.75 inches. I just realized that he is now longer than the tank is wide. He is over 18" and about to get moved into a 210. My 7 year old fish grew 4 inches in a year!!!! Good grief, when will he stop growing?