First you need to know that there are 4 species of 'giant' gourami (members of the genus
Osphronemus)
They are
O. goramy, O. Laticlavius, O. Septemfasciatus and
O. exodon.
The largest is
O. goramy which gets to 28" typicaly; but larger is quite usual. This is probably the fish at your LFS. I tried to look up the largest size on record but I could only find the world record for weight (based on what fishermen have caught) - it's quite impressive at 5.6kg - the typical weight is around 5kg.
Laticlavius and
septemfasciatus grow to only 20". The former is quite common and sold under the name 'giant red-fin/red-tail gourami'. The latter is much rarer and I couldn't even find a google image of it
O. exodon is mid-sized, growing to around 24". It is especialy unusual because it has enlarged teeth, unique amongst gouramies.
All four species are similar in requirements and disposition. I am most familiar with
O. goramy, which is also the most common. They can be quite aggressive as juveniles, becoming increasingly calmer as they mature. However, they are still territorial at adulthood and do require a large tank and sturdy decor if they are to be kept with other fish. Usualy, large fish that can look after themselves but are not aggressive are suggested - things like catfish, including large plecs, usualy make good tankmates. Food-wise, they are mainly herbivorous but will eat pretty much anything. I would suggest a minnimum tank size of 200 gallons for one individual. other people may reccomend less but I personaly feel anything smaller than 200 gallons is very cramped for a fish that's over half a meter long, very heavy and produces vast amounts of waste. Not to mention that they grow very rapidly if given the space.
I personaly think these fish are adorable
There's only one stage - which perhaps might be comparable to 'adolescence' - where they look somewhat 'messed up'
Before then they are very cute juveniles and afterwards they grow into beautiful, impressive adults. I would absolutely love to own one - if only I had the money and space!!!
For pics, you could do a google search (if you haven't already). I think the best ones are those with a human in them for size comparison
