Every female I had, had a black patch in the dorsal. Usually a dead giveaway.
Heres my beast of a male... he doesn't stop growing .. hes around 3 years old and really starting to beef up. He never had black on his dorsal . those younger ones look male to me
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Wow that is an awesome looking male. OP great potential in those little guys.he is my giant pink fish ... he sure acts like a bull moving the driftwood everywhere and constantly begging for food. Yours will look like that in no time at all ! Make sure you stuff them full of nightcrawlers every once in a while that's what I did to get him so fathe also enjoys catscrapers quite a bit .