To trigger the breeding behavior, in the late fall perform a 75% water change with cool water, simulating the influx of colder water the rainy season brings in nature. One aquarist reportedly bred this catfish in water as cold as 64.4° F (18° C), though he said they didn't really like water that cold. A breeding tank can be 10 to 20 gallons or more with plenty of caves and driftwood. A mature male needs to have plenty of room to claim a territory that is most suitable for spawning. The recommended water conditions are slightly acidic with a 6.5 - 7.0 pH and 5 - 10° dGH.
As a common pleco isn't cold water
Coldwater fish, in the context of , refers to species that prefer cooler water temperatures than , typically below 20 °C (68 °F). Some examples are and . These species tend to grow more slowly and live longer than fish that live in warmer waters, and are generally felt to be easier to keep.
Can a common pleco survive in coldwater? - Monster Fish Keepers
Apart from plecos, I would also recommend a few nerite snails. I wouldn’t recommend any other fish algae eater, because they would most likely get eaten and are mostly warm water fish while goldfish are cold-water fish.
Is there a cold water plecos? - Monster Fish Keepers
As long as you have a “common” species from your pet smart or petco you should be completely fine. Actually these common plecs are taking over the swamps of florida water holes becuase some aquarists have been letting them go and they are now breeding and taking over in the ponds. Lots of people keep them with goldfish tanks and goldfish are considered “cold water” fish so you should be fine.In an environment large enough and well maintained, tank mates selectively chosen from the subtropical and coldwater species can make good compatible tankmates for goldfish. There are a couple of other considerations however, such as fin nipping, aggression, and other compatibility issues just as you would have in combining different types of tropical fish.I live where temperatures drop below freezing for most of the winter, and often, below 0. Without help, thepond would freeze over completely. The deepest area of my pond is about 32 inches. I keep a strong fountain running all year round, and in the coldest days and nights I supplement with a surface heater to keep an area open, when the running water isn’t enough.
My fish have no interest in food during the winter.
I haven’t lost a fish to winter in the seven years I’ve had the pond. All are shebunkin and one other variety, whose name I can’t recall at the moment. Sorry.If you just got a cold water one (so no heater) you will only be able to keep little fish, minnows, barbs, danios for example. Absolutely no goldfish as the biorbs are completely unsuitable for them. Stocking levels for goldfish are as such: