Goldfish spazzing in 5-gallon tank? Is it the water quality?

A 5 gallon tank is insufficient for goldfish. They produce a larger than normal bio-load (wastes) that can quickly overwhelm a small tank. Ideally, one goldfish should be in a 20 gallon tank with an extra 10 gallons added per additional goldfish. The filter should be rated for at least twice the volume of the tank. They are likely succumbing to ammonia and/or nitrite toxicity. If you test the water, it is likely both parameters will be dangerously high. Perform a 50% water change. Use only conditioned water that is temperature matched to prevent further stress or shock. Goldfish are cold water fish and do best between 65 F and 72 F. Plain aquarium salt, NOT table or Epsom salt, can be used to reduce stress, improve gill function and aid in recovery. Dissolve 1 teaspoon per gallon in a cup or two of tank water and gently pour it into the tank. Treat for no more than 14 days then perform a partial water change to decrease salinity. A 5 gallon tank would be appropriate for one male Betta or a small school of Neons (3-5).

Thanks for reaching out about Goldie. There are two concerns here: (1) not apparently eating and (2) high ammonia. For the appetite, try to note if there is feces. If feces, then eating. If appear getting thinner, then not eating enough. For the second problem, this is probably new tank syndrome, and not allowing the biological filter to establish. Water changes are needed to bring down the ammonia as that is toxic to the fish and damaging to the gills. Probably the reason for the frantic swimming. Good luck.

This could be due to having a tank that is too small. 6 goldfish in one tank poses several potential issues. Ideally, 1 fish should have a 20 gallon tank with an additional 10 gallons provided per extra fish. This would mean they should be in at least a 70-75 gallon tank. The reason being goldfish produce a larger than average bio-load (wastes) that can quickly overwhelm a small tank and filter. Poor water quality can lead to stress and infection as well as behavioral issues. Depending on their sizes, the present tank could be overstocked leading to bullying and fin nipping. Check the water quality and chemistry. Use a home test kit or submit a water sample for testing. Most pet stores will do this for free or for a small fee. Aim for an absence (0 ppm) of ammonia and nitrites with a nitrate level of 20 ppm or less. Perform partial water changes, if indicated, to stabilize chemistry and maintain or improve water quality. Use only aged or conditioned water that is temperature matched to prevent further stress or shock. Goldfish are cold water fish and do best between 65 F and 72 F (18.3 - 22.2 C). Make sure the filter is rated for at least twice the volume of the tank. If possible, separate out the aggressive goldfish to a different tank to prevent further bullying and injury.

Thanks for reaching out about your fish. Typically, most recommendations are 1" of fish per 3 liters of water. The better the filter system, the better the water quality and the more biomass can be handled. Remember, fish grow and therefore the biomass will increase. Good luck.

It could be an infection or tumor. An infection may be resolved with proper treatment but you would need to get Rory and the other fish out of that small bowl. It is much too small for one goldfish, let alone three. Goldfish need large tanks because they produce larger than normal amounts of waste. Ideally, 1 goldfish should have a 20 gallon tank. Add an additional 10 gallons per extra fish. That would mean you need at least a 40 gallon tank. You also need a filter in there. The filter should be rated for at least twice the volume of the tank. To keep them in a small bowl will drastically shorten their lifespan and could lead to stress and illnesses.

Hi, and thanks for your question. There is a general rule about it which is a rough estimate not to overcrowd your aquarium and avoid excessive production of feces and organic debris. The rule is one Inch per gallon, so in 10 gallons there should be ideally 10 inches of fishes in total. You should consider as well the presence of plants and gravel and any other sort of things, which decrease the water volume of 5-10% (so 10 liters are actually 9-9.5). This rule does not consider modern filtration systems. These fish suffer genetically from a certain grade of visual impairment, so overcrowding (especially competition for food) is not recommended. At the same time, please consider as well that schooling fish (like they are) should be kept in numbers, which means more space will be needed, so be generous.

Thank you for using Petco Pet Education Center, formerly Petcoach! It looks like the tank provides enough room for Speedy and Explorer to swim comfortably. Keep an eye on them, and move them into a larger tank if they get significantly larger or you notice signs of fighting or increasing ammonia levels in the tank.