So a friend gave me a 55 gal planted tank when he moved recently, complete with fish. I've mostly owned various cichlids up til now with some other ventures into less aggressive species. This tank came with 3 angel fish which I promptly donated to my LFS (lol not a huge fan of angels, they actually came from the store I gave them to, a very reputable place) and one BGK, around 5 inches, which I am quite intrigued by. So this wasn't a tank my friend paid a huge amount of attention to, but the knife has already begun hand-feeding on blood worms. Very hungry fish here. My question is pretty simple: How fast will the little fella/girl grow and how long will the 55 gallon be suitable? I'll shoot my friend a text to see how long he's had the knife already, I know the tank was around 8 years old. I have to assume the fish was a fairly recent addition since apparently they grow much larger than this. Anyhow, any suggestions are appreciated.