I have been keeping tropical fishes for the last 6 years. I have had several Balas in that period. Bala Sharks are very active fishes and they can eat any thing that you offer to them. They are very peaceful and look very beautiful, especially when they adopt their full colors. Sometimes they got blackish shade on their silvery shiny body because of being nervous by other fish or maybe anyone at your home. They can attain size of 40 to 45 cm. Presently I have 6 Bala Sharks in my 180 cm long aquarium. Two of them have attained a size of 30 cm, others are not less than 20 cm. They are very peaceful. Sometimes they show their typical behavior and get aggressive against other fishes. Balas will do better in a large aquarium. They can attain their full size and health in the large aquariums rather then a small one. You can have trouble keeping some real plants in the aquarium of Bala Sharks because sometimes they eat the real plants. One more important thing about Bala Sharks is that they swim like flash from one corner to another corner of the aquarium, so it must be ensured that there are not many rocks in your aquarium, as they can be injured by colliding with rocks and can lose their beauty to some extent. One more last tip that I would like to give all of you is that for attaining a good size, shape and colors of your balas, you may offer them fresh foods such as beef heart, prawns, chooped meat, etc. This will really work for betterment of your fish, but along with offering these foods you must ensure about the efficiency of your filtration system that you have in your aquarium, as well as you will have to change 1/4 water of your aquarium at least twice a month, otherwise your aquarium can be affected by nitrate.
I have 3 Balas that are huge. After buying them small I have learned what to feed them to gain rapid growth. I feed them Veggie Flakes. You can see growth within 1 week. My biggest Bala is about 40 cm, the next is around 33 cm and the smaller is about 18 cm.
These fish are great! They eat almost anything. One of mine is weird. If another bala shark comes near his algae pellet, he quickly scares them off, but when a neon tetra or another fish starts nibbling on his pellet he politely waits for them to move or finds a new spot on the pellet, but he gives them a scare when he makes the clicking sound. I plan on moving these guys to a 470 liter!
These pages have enough comments to give the reader a basic idea on the topic. Further comments are still very welcome (through the site's contact form) as long as they provide new and/or advanced information not yet discussed in the existing ones.