Putting other coldwater fish in with goldfish is not just a matter of going to the petshop, buying anything that can survive in coldwater and putting it in with goldfish. A whole world of problems is just around the corner for those who think it’s anything other than advanced goldfish keeping.
Before going on to different fish species, it is worth repeating the fact that narrow-bodied and fat-bodied goldfish varieties should not be kept together. The narrow-bodied goldfish such as common, comet and shubunkin will have eaten all the food before the fat-bodied ones (most fancy goldfish) realise it’s feeding time.
Also, before introducing any new tank mates, make sure to quarantine them properly beforehand. Non-goldfish tankmates for goldfish have the potential to cause enough problems already without disease being one of them.
Another thing to be aware of – if the other species of fish can fit into a goldfish’s mouth, it will end up in a goldfish’s mouth.
The hillstream loach is perfectly adapted for latching onto a surface and facing into a strong current. Their natural habitat is fast-flowing streams, and they have a perfectly streamlined body. Their perfect tank environment has a strong pump creating a current. Because of this it is impossible to keep both goldfish and hillstream loaches in their ideal conditions. Goldfish are not built to deal with a constantly strong current.
Like all algae eaters, they need to be fed away from the goldfish. The best plan is to feed the goldfish at one end of the tank, then drop in some sinking food for the loach at the other end. A varied diet is best for them, but algae tablets and sinking pellets should form the basis of their diet.
One nice feature of the hillstream loach is its ability to change colour according to its surroundings.
Weather Loach aka Dojo
The weather loach is a slender, fast fish that can grow up to 6 inches long. They scavenge around the bottom of the tank, and thrive where there is fine gravel to root around in.
They can dart extremely quickly and have been known to leap out of goldfish tanks. Obviously this is fatal if not witnessed. It is a good idea to have some sort of cover over the water to prevent this, and only to uncover as much of the surface as is necessary when performing any aquarium maintenance.
When weather loaches are not sitting at the bottom of the tank, they do enjoy swimming in and around tank ornaments. These ornaments can cause injury to fancy goldfish that have protruding eyes.
Corys are a type of catfish, and there are over 10 common cory species. They usually sit close to the bottom of the tank, not doing very much. Occasionally they will go for a swim, but will usually sit about doing very little.
Most cory species sold for goldfish tanks are not the type of catfish that can grow bigger than a man. In fact they will not usually grow beyond 3 inches.
Like loaches they are bottom feeders, and need sinking food chopped up small. They generally get on well with goldfish, but if not fed properly will suck the protective slime coat off goldfish. This is a disaster if it happens. The slime coat protects against all manner of goldfish illnesses and diseases, and its loss can be catastrophic for goldfish.
White Cloud Minnows
White cloud minnows are small fish that grow to about 1 inch long. They are social fish and should be kept in shoals rather than as individual fish. This feature makes them an attractive addition to an aquarium.
They will eat the same food as goldfish, and do not need fed separately as they can swim fast and can compete.
One thing they do like is a hiding place somewhere in the tank.
The main problem with white cloud minnows is their size. When goldfish grow big enough, they will almost certainly eat them.
There is one other species of fish that is often said to compatible with goldfish – the chinese algae eater. However, it is a tropical fish and although it has been kept with goldfish with moderate success, it is not recommended.
The only other species that can be kept with goldfish are snails. The most attractive one (subjective of course) is probably the golden apple snail.