Ya, but these fish slow down significantly in growth when they get to that 18'' mark. Just ask mel about it, it specifically talks about how his huge dovii will grow till the day he dies, but has slowed down quite a bit.
Now, in regards to the umbee from Columbia, if it truly was bigger than the 24'' mark it would of surely made the list. But obviously if it wasn't verified than it is just pure speculation. Look, you guys can say there are 30'' umbee out there, but the fact remains, NOBODY has ever caught or been able to prove such a claim. The end of the day, you must go off of facts. The fact is, the dovii is larger than the umbee, it is verified, and proven. Until otherwise, everything else is speculation and nothing else.
Mel also had his umbee in a 600 gallon with the festae pair I believe.