Truth is nobody can tell you what they will actually max out as because each ray is individually different during growth and development. I honestly play it as any type of ray in the marble Leo mantilla Henlie motoro pearl castexi or others can hit only say 15-17 inches ish, or stay even smaller like the mini marbles and I have a mini male mantilla. 9.5 inch breeder, but also at the same time they might very easily hit 24 inches. In my opinion mantilla grow slow and don't get super big but is it possible to get one that hits big of course. I can remember seeing a few breeders in other countries that were 24 inches or bigger.
A 30 inch tank will be plenty for a long long time or forever.just never know till you get 3-4 years down the road.
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