They are a very HARDY fish and live many years (10+ years). No worries. a Very easy fish to take care not only because the water quality does not have to be perfect...but they ignore all other fish in the tank, so no aggressiveness.
There is also a "Glass tinfoil" but i have no clue what they look like because there is no pic on the internet.
The Albino's are not as Hardy because they are albino (throughout all species, albinos are harder to keep alive) SO IM NOT SURE ON THEIR LIFESPAN.
you change quite a bit of water often which is good. Most don't change this much but probably should. Do you have any close ups of your albinos, I think you posted some photos before but not close ups?
People may have problems with tanks sizes. any tank 60 gallons or more is fine for tinfoils. Yes..they wont reach their natural size? does this harm their health? I dont think so. Bala sharks are schooling fish, BUT THEY GROW HUGE. People still keep them and they live a peacefull life in a tank where a fishkeeper shows their love, instead of in some pond in ASIA waiting to be served on someones dinner plate.
BTW: DO NOT KEEP ONLY 1 Tinfoil!!! Important!! I heard HORROR stories on the newsgroups where single tinfoils will terrorize all the other fish in the tank... 3 or more does not show this behavior.....
I'm sure you could put some in a medium sized aquarium such as a 55 or so. They just would not get quite as large as say a 200 or 300 gallon. I've had the tiny aquariums before like 55 gallons, my next tank I want a 300 gallon.