Be careful with your bioload! Also, lions grow at an explosive rate, and their sting hurts! They are awesome to watch eat though. Are you planning on upgrading because once a lion is full grown it will touch the front and the back glass at the same time. Of course you could trade it off at that point, I would just be wary of not giving your fish enough room to truly ensure a good life for it. True maroons are a dime a dozen, you should be able to find a 3" no problem. Look on Live Aquaria it's a great place to buy from online! Best wishes and good luck! Listen to Jeremy, he is very knowledgeable, do not doubt it!