bala sharks do look cool, however your tank and even a 29gallon tank are to small. balas can grow to about 12 inches.
for freshwater a rough guide rule of thumb is 1 gallon per 1 inch of fish
you might be "ok" with him in there temporary but i wouldnt keep him in there for any period of time.
rtbs's can grow to about 4-5 inches and get pretty aggresive even in larger tanks.
for a bigger tank, if your located in the united states, check your area on craigslist.com ..take your time looking for that deal, because you can get a larger tank for a good deal and alot of times you get peoples complete setups.