Even under very favourable conditions, good size tank, good diet, regular water changes etc I don't think anyone will experience fantastic growth with clown loach. Growth wise they are about as frustrating as it gets.
From my own experience, and also from what i've read, it seems that most hobbyists tend to witness a relatively fast growth rate from the 2" shop bought fish they've got up to about 5". Then they seem to stop at 5" and anything onwards from that is incredibly slow. Mind you, when I say relatively fast i'm talking 2" to 5" in about 3-4 years so still very slow but nothing like as slow as their growth from 5" onwards.
I'd be very interested to hear if anyone has experienced anything different than that, and how, or what did they do to encourage improved growth.
And
RD.
would their growth rate in the wild be similar to aquarium growth rate given that it pays to develop faster in the wild to avoid predation. If it is slow in the wild maybe they shoal up in huge nursery areas when they're juveniles with lush planted areas to stay clear of predators?