I have a very odd little fish, and no idea as to why, so I'll share with you experienced, advanced fish hobbyists, and hopefully receive some insight.
In Noverber 2006, I bought 4 young Albino BN Plecos at a fish auction. All were about 1 inch long and healthy. They did well and all but one grew quickly to about 5 inches. By March, they were obviously 2 males and one female, so I paired them off with unrelateds.
However, one never seemed to grow at all. It's fat and healthy, but still barely 1 & 1/2 inches long. I put it in a 5 with a few adult female Gups, just to see if it might put on some additional size with no competition, but after 3 months of vigorous feeding, it still hasn't grown any larger.
Is it possible that this fish is a true dwarf? If it has reached full maturity, it's a female and if I could find a male small enough, I'd pair them off, just to see what I'd get.
I do have several "dwarf" BN's: one a very pretty white spotted green male, but even he is twice the size of this tiny mystery fish.
BTW: It (she?) is quite active and gloms into food with gusto, lashing her tail with obvious aggravation if any full grown female Gup twice her size tries to horn in on the treats, so lack of all the food she could possibly eat can't be the reason for her diminutive size.