Providing that your goldfish are properly cared for and you keep them in the correct environment, they should not suffer from illness.
To keep your goldfish happy and healthy, you should follow these basic rules:
- Do not overcrowd your tank
- Ensure there's at least 10 gallons of water per goldfish
- Change the water every week to keep ammonia levels down
- Keep the temperature between 20-24 degrees Celsius
- Feed your goldfish a varied diet with the usual flakes/pellet, fruit and veggies
- Do not overfeed your goldfish — feed twice a day
- Do not add other contaminated fish or plants in your aquarium
- Do not handle your goldfish
- Make sure your goldfish have time with the lights out so they can sleep
It is also important that you try not to frighten your goldfish or stress them out whilst either cleaning their tank or interacting with them.
Goldfish can hear, so don't tap the sides of the fish tank, and because water carries sound far better than air, the noise can be quite loud and frightening to them.
Check to see where your goldfish swims — if they swim near the surface of the water in the tank they could possibly have a problem with their swim bladder. Consult a vet if this is the case. The purpose of the swim bladder is to help the fish rise and lower himself in the water. For example, when he wants to go up, he fills his swim bladder with air, and when he wants to go down he'll release the air. This is why you may see your fish blowing bubbles as he descends.
Signs of a healthy goldfish:
- They swim in clear, clean and odourless water
- Expanding their gills regularly
- Eating regularly and approach the surface quickly at feeding time
- Swimming actively throughout the tank
- Do not have white spots or blemishes on their body
- Healthy looking fins that aren't torn or ragged
- Brightly body colouration.