Wow, I think I've never heard of anyone putting one in a 15 gallon tank.:headshake2:
He should be 4" and nice and round by 6 months of age, should be 5-6"by 1 year of age. It'll never work. He will get stunted, heaven only knows how him and the betta will get along, he'll be lonely for more of his own kind, if water quality is not kept up to par he'll be at risk for a number of serious ailments, and did I mention he'll get stunted? I understand not being able to resist temptation when people see them in the fish stores, and even if you could only keep one because of the expense of them, keeping in that small of a tank is defeat before you start. They are definitely not a fish to be picked up, plopped in a tank and kept hap-hazardly.:headshake2: