By combining the wrong goldfish varieties in the same aquarium, a host of problems can result:
- Goldfish bullying
- Slower goldfish not being able to feed properly and starving as a result
- Goldfish stress
- Goldfish with poorer eyesight not locating food quick enough
- Fancy goldfish varieties have been bred to look good, but often cannot swim very well.
That means they can't get to food as fast as other varieties
For instance, Comets are the fastest variety of goldfish.
If you mix them with slower types like Moors, then Comets will always get to the food first.
A Moor simply won't be able to "wobble" their way to the food quick enough to feed.
If a goldfish is persistently "knocked out the way" by a faster goldfish or consistently cannot get enough food, they become stressed.
Goldfish stress and bullying happens frequently.
And it means that a goldfish will become quiet or lie on the bottom of the tank.
Unlike people, a goldfish cannot tell you he is sick or stressed; often the only sign that something is wrong with a goldfish is that they become still and stop feeding.
Faster goldfish also have a tendency to move around at high speed without warning.
They can inadvertently bump into the slower fish.
This can become an issue as breeding season starts, when better weather arrives.
The mating ritual of goldfish is essentially the male chasing the female.
He constantly nudges her to release eggs, so his "milt" can fertilise them.
This is very tiring for any female goldfish, but for one that is far slower and has poorer eyesight, it can become quite distressing.
If the slower goldfish is the female, and the faster one a male, then they will be constantly chased around the aquarium.
This breeding behaviour can last for days.
Even with Common Goldfish, you have to monitor them to make sure they don't injure themselves.
It is common to lose scales during the breeding "chase".
And you want to keep your pets healthy to avoid any goldfish diseases care being necessary.
So faster fish, like Comets, are generally best kept by themselves: they are too fast to be mixed with slower varieties - and they are greedy feeders.
There are also many varieties of so-called "fancy goldfish" and these need extra goldfish care.
Some, like Orandas, have a sensitive digestion, as well as a gentle disposition.
They are also much slower, aerodynamically, than faster fish like Comets.
The reason for is they have been bred to ensure they have long flowing tails and to accentuate certain features, like eyes, fins or a "compacted" body.
This makes them more susceptible to getting Goldfish Swimbladder Disease than Common Goldfish.
It also means they can't swim as fast.
This is doubly so for goldfish lacking a dorsal fin: Lionheads and Ranchus.
These struggle to maintain equilibrium in the water and are poor swimmers.
Fancy goldfish varieties like Orandas and Ranchus need their own aquarium.
Smaller slower-swimming goldfish, like Moors, also need to be kept separate from faster fish like Comets or Common Goldfish.
It is important to ensure that goldfish can feed well, and don't have to compete unnecessarily at meal times.
The necessity for goldfish diseases care can often be avoided by carefully planning the varieties of goldfish that will be together.
As a rule of thumb, only keep goldfish in the same aquarium if they are similar in type, size and speed.
And there will be no need for goldfish remedies.