In average, you can keep about 3–4 goldfish in 30-35 gallons of tank, though this number will vary depending on fish sizes and water filtration system.
When it comes to keeping goldfish, there are a lot of things to consider. One of the most important is the size of the tank. A smaller tank might be easier to maintain, but it won’t accommodate as many fish.
A larger tank might be more expensive and require more effort to keep clean, but it will give your goldfish the room they need to thrive.
What Affects The Number of Goldfish You Can Keep In A Tank?
Goldfish Species: Different varieties of goldfish have different development rates and sizes, affecting the quantity you may keep. For example; Fantail, Oranda, and Comet goldfish grow slower and stay smaller.
Tank Shape: Rectangular aquariums provide more space and fewer corners for goldfish to navigate. Rectangular tanks are better for keeping more goldfish than cylindrical or square tanks.
Decorations & Plants: Live plants are the best tank decorations. To maximize fish in your tank, utilize minimum décor. Too many decorations restrict fish swimming space. It creates more hiding spaces for uneaten food, affecting water quality. A 35-gallon aquarium with little decorations is best for goldfish.
Water Quality and Filtration: Poor water quality can sicken and kill fish. Don’t overfill your tank. If your water quality is deteriorating, you must act promptly. Adding a filter or doing additional water changes may help.
Stress & Disease: Overstocked goldfish tanks can cause stress and sickness. Fish stressed by lack of space. Stress can lower your fish’s immune system and make them sick. Stress causes ragged fins and whitish bodies.
Aggression: Due to overcrowding fish often fight. Aggression can cause fighting and death. When confined, goldfish become aggressive. When stocking your tank with goldfish, ensure each has adequate space to call its own.
How Many Goldfish in a 30 & 35 Gallon Tank? Explained
The size of the tank is important, but it’s not the only factor to consider. The type of goldfish you have will also affect how many fish you can keep in your tank. Goldfish come in two main varieties: fancy goldfish and common goldfish.
Fancy goldfish are the ones with the long fins and bright colors. Common goldfish are the ones that look more like their wild ancestors.
Fancy goldfish are generally smaller than common goldfish, so they don’t need as much space. A good rule of thumb is that you can keep one fancy goldfish per 10 gallons of water. So, if you have a 30 gallon tank, you could keep 3 fancy goldfish. If you have a 35 gallon tank, you could keep 4 fancy goldfish.
Common goldfish are larger than fancy goldfish, so they need more space. A good rule of thumb is that you can keep one common goldfish per 20 gallons of water. So, if you have a 30 gallon tank, you could keep two common goldfish. If you have a 35 gallon tank, you could keep three or four common goldfish.
There are other factors that can affect how many fish you can keep in your tank, such as the temperature of the water and the amount of filtration your tank has. But in general, following these guidelines should help you determine how many fish you can comfortably keep in your 30 or 35 gallon tank.
So, how do you decide what size tank is right for you?
Conclusion
In general, however, a 30 gallon tank can comfortably house three to four fancy goldfish or two common goldfish, while a 35 gallon tank can house four fancy goldfish or three to four common goldfish. Whatever decision you make, just be sure to provide your fish with plenty of space to swim and plenty of clean water to live in!