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The Goldfish Gazette, Issue #062 -- Aggressive Goldfish
February 28, 2019
Goldfish Care Tips
A Free Monthly Resource For Goldfish Enthusiasts
In This Issue
Goldfish by nature aren't aggressive, but if unsuitable tank mates are put together, some smaller individuals may be injured or worse, killed.
Aggressive may be too harsh a word. Perhaps the word energetic is more suitable.
This E-zine subject has come about because two of my young Water Bubble Eyes were killed by a larger, single tailed Water Bubble Eye.
One of the smaller WBEs was in the sickbay recovering from dropsy, and the other was in there as a precaution.
The larger fish was put in the sickbay because of a clogged nasal orifice that had started to become inflamed.
The size differences weren't that great, and there was no possibility of the larger fish eating the smaller ones. Normally I would have put the larger fish into a separate aquarium but because it was just after the breeding season, I had most aquariums full of fry.
The larger fish has collapsed water bubbles so is essentially a Comet without a dorsal. It is a very active fish.
I checked on the fish the next morning, and both the small fish were floating on the surface. I will spare you the details but it was a most upsetting sight. I have never lost fish this way before.
Mixing Unsuitable VarietiesI have often discussed in the past how single tailed fish should not be mixed with twin tailed varieties, and normal eyed varieties shouldn’t be mixed with moors, Water Bubble Eyes or Celestials.
There is another factor that should also be considered, the energy level of the variety.
I was watching a video on one of the Facebook Goldfish groups, and the owner was feeding her fish. Large Comets and Koi swept in and out of the feeding circus at great speed.
What I noticed was a small calico Fantail at the bottom of the feeding frenzy, hoping some of the pellets would sink down. They didn’t. The koi and Comets cleaned them off the surface in seconds.
Watching my Celestials when I drop food into their aquarium is amusing to watch. They can smell it, but can’t see it so charge around the aquarium until they stumble across the food that has settled on the bottom.
Imagine if a Comet, or any normal eyed variety was in their aquarium. The Celestials would always miss out on the majority of the food.
Matching SizesIf you combine energy level with size difference, you could easily have the same situation I had with the Bubble Eyes.
Many Goldfish group members report their fish losing an eye, especially moors. Most put this down to injury caused by the fish colliding with something in the aquarium. Interestingly, the owners don’t report finding the eye.
I have never had a moor lose an eye from bumping into something in the aquarium. I wonder if it isn’t a larger fish having a quick bite at a smaller fish.
During feeding, fish that have missed out often bite at fish that have mouths full of food. With fish of the same size, this isn’t a problem, but if there is a significant size difference it could be. By size difference I don’t mean just body length. A 100mm Comet is twice the weight of a 75mm fish, something I didn’t consider when putting the larger fish in with the smaller ones.
In SummaryWhen mixing fish of different varieties, also consider the energy level and size of each fish.
Even fish of the same variety can have large differences in physical characteristics. Fantails can have short, long or veil (broad) caudal fins. A Veiltail will always be at a speed disadvantage compared to the short-tailed fish, especially as it gets older and its fins attain their full size.
Comments? Ideas? Feedback? I'd love to hear from you. Just reply to this e-zine and tell me what you think, or what topics you want covered.
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