mine almost got me today when i was bagging him up, the 2 people working there were scared to even bag him for me !! he was actually sold as P. Volitans but when i compared them in my book .... he is in fact a spotfin. i would say that either tank will be big enough because they will only reach ABOUT 8", as where their cousin (volitan lion) reaches 15".

anyway, congrats on your new fish and good luck, but they are very hardy.