Fish Acting Funny/Dying

Question
I have (2) large gold fish about 3 weeks ago they started not swimming around and acting funny and when they do swim it is like they do not know where they are going. Ph & ammonia are good, temp of the tank is 79 degrees. Bought (2) Bala sharks, they lasted 72 hours and they died. The (2) gold fish are just laying at the bottom of the tank but swim good if I put a stick in and make them move. These gold fish are 5-7 years old. Does not seem to affect the small feeder fish (gold fish) in the tank or my plako. I am baffled. Have had this tank a minimum of 14 years and never had a problem. Help, Thanks.

Answer
Hi Beverly,

I'm sorry to inform you that you have a huge problem with your tank. First of all, Goldfish cannot be kept with tropical fish, such as Bala Sharks. Balas need temperatures of 75F and above, while Goldfish need temperatures of 70F and below. Your tank temperature is much too high for Goldfish. You might want to get bottles of cold water and place them in your tank.

How big is your tank? It should be at LEAST 20 gallons (76L). Common Goldfish will reach a size of 12" (30cm), while Comets will reach a size of 24".

If you plan on keeping the Pleco for his whole lifespan, you will need to get a larger tank. They will grow to an adult size of 24", and require a tank size of 50+ gallons.

Change 20% of the water daily for one week, then after that, change 10% of the water every 2 days until the problem resolves. You must get the temperature down! This is extremely stressful to your Goldfish.

Good Luck, and Happy Fishkeeping!