compatability and diseases

Question
QUESTION:     First, I would like to ask about a fish I already own. It's a Bala Shark. We've had him for about 9 months now. He's swimming funny, and he has what looks like injured scales, a few scales on one side are darker, they actually look like they're missing, and he's not going for the food when I feed. I was wondering if you know what he has, and the possible solution to get him well again?
   Another question, Is to find out if a Freshwater Puffer is compatible with what I have in my tank, I have in my 55 gallon tank 2 blue gouramis, one golden gourami, 3 rainbow shark, 2 polkadot pictus, 1 farluala, 1 plecostomus, 2 albino catfish, and two algae eaters? If so, what kind of water conditions are best for the freshwater Puffer (ph,alkalinity, and temp.)? How do I look for a healthy one from a local pet store?

ANSWER: First, the puffer depends on the type. There are a few types people call freshwater puffers but most are actually brackish, meaning they like saltier water. Let me know the type and I will help you out with that. As for the bala shark, is there a bully in the tank with him? If so he may indeed be picked on leading to the missing scales and the stress. Or does he dart on rocks or plants, does he have any other signs? If not, than he prob is being picked on. Let me know more detail and I will try to help you more.

---------- FOLLOW-UP ----------

QUESTION: The puffer has the name of "Freshwater Leopard Puffer"
The bala shark is in a tank with some pretty calm fish, and I haven't observed any bullies picking on him. He's been swimming better than a few days ago, but he still is not interested in food (all kinds of assortments). He seems lethargic, a few days ago I noticed that he would just let the water take him in any direction, even to an almost floating upside down position, then he would come out of it and swim upright, and his head would kind of wag back and forth as he swam. But not darting on rocks or plants. Now he seems a little more in control by not letting the water push him upside down, just lethargic. The scales that were darker seem to be lightening up slightly.
Tank size: 55 gallons
Inhabitants: bala shark (had for about 9 mos.),
         zebra danio ("        "   1.5 years),
         2 neon tetra (4.5 years),
         farluala (1.5 years),
         2 albino rainbow shark (4.5 years),
         1 rainbow shark (1 year),
         2 algae eaters (1.5 years),
         2 polkadot pictus (9 mos),
         2 albino catfish (4.5 years),
         2 blue gouramis (9 mos),
         1 golden gourami (9 mos),
         1 7in. Plecostomus (4.5 years),
         several small snails (continuously are  
         breeding, and being eaten).
Tank age: 2 years, 3 months

And, would the fish in that tank be compatible with baby "Freshwater Leopard Puffers"? Would I need to add salt, and if so would the salt affect the other fish in a bad way?

Answer
The bala shark is something that puzzles me. While they do sometimes let themselves be taken by the water I have not seen one let itself almost go upside down. But I have a bala shark right now who has some missing fins and he is just fine, I assum it was one of the fish picking on him or he got injured by something in the tank. If there are no other signs I am not sure there is a way to figure out what is wrong with him. Just keep me posted as to the condition of him and if he develops any new symptoms. As for the puffer, yes they do prefere salt. While they can survive without salt, they do much better with it. Also, it WILL hurt your corys catfish, they can not handle salt. Also, the puffers are not community fish and do much better and its safer to keep them by themselves or with other brackish fish (half salt half fresh). I would suggest getting a smaller tank and providing them with their own habitate if you really want them. I myself am going to get one and put it in a solitary tank so I can have them without the possibility of hurting the fish you currently have. It would be in yours and your fishes best interest to not add the puffer to the main tank. Let me know if you need more info. I hope I have helped you.