55 gallon goldfish tank help

[GoofyGarra]

For some context: My friend and I are in the process of setting up a 55 gallon tank for a school. At the same time, someone contacted my friend that they no longer wanted a tank and needed somebody to get their tank and fish. My friend and I decided to make things easy, to put some of the rescued fish into the 55 gallon tank.

A few questions. The stocking of the rescued fish includes 5 goldfish, 3 mollies, and a swordtail.

• How many goldfish is a good amount for a 55gallon tank? Perfectly aware there is never a black and white answer to this question, but looking for a safe number assuming monthly water changes and good filtration.
• Should we heat the tank or not? These appear to be common goldfish which tolerate cold water, but is there any advantage heating the tank?
• Tankmates? The goldfish being the centerpieces of the tank, could the mollies and swordtail go in with them as well? Or just mollies? Or just the swordtail?

Thanks!

 

[EggShappedFish]

On 3/8/2024 at 12:09 PM, GoofyGarra said:

These appear to be common goldfish which tolerate cold water

IMO, these should not go into a 55gal or an aquarium at all. The reddit godlfish community suggest the following for common goldfish:

The general standard is 55-75gal (208-283l) for the first one and 20-30gal (75-113l) for each one after that. (ref)

That said, the minimum is what barely can be managed by experienced goldfish keepers, and with very regular water changes. For fancy goldfish, tanks are much better suited, but commons are very good and fast swimmers. Ideally I'd look to rehome them, to a place that has a pond for them.

As additional info, mostly relevant for fancy goldfish, heating water for goldfish, is generaly widely discussed. Some keep them warmer, to boost growth, but this ads to the bio load and will require a lot more filtration, aeration and space. It is also considered as a factor that shortens their life.

Tank mates (ref) are not recommended but often tolerated. They will eat smaller fish, that are not fast enough, and be bullied by larger fish. Especially eating smaller fish, can be hazardous, in particular with coridoras. Also plecos are often ill adviced. Although many do use them, there are also instances of them really damaging fish, while they sleep. Best goldfish buddies are goldfish, and preferable goldfish with similar swimming abilities (personally i wouldn't even mix fancy and common goldfish)

 

Edited March 8 by EggShappedFish

[mynameisnobody]

I have a 300 gallon stock tank with 10 wakin goldies, assorted platies, and some endlers that somehow got in there. As for tank mates, personally I’d stick with smaller livebearers. The Goldie’s can pick off fry or even give chase for some mental stimulation. Now as for a 55, I would be a bit cautious because it is quite narrow. With that said, if I absolutely had to, I’d put 2 in there but it’s pushing it. They get large and the filtration requirement can get intense if you skip a water change or 2. Good luck, school aquariums are amazing. 

[GoofyGarra]

@mynameisnobody@EggShappedFish I appreciate your replies. On further thought we will just be keeping the goldfish in the 55gallon temporarily until we can find someone with a pond.