One of the first axioms of goldfish keeping is, “don’t keep everything in the same place”, by this, it is meant that if you want to avoid disaster, spread your stock out among different tanks, tubs and ponds. The first corollary to this might be “Don’t subject everything to the same treatment”. Whether you follow this advice intentionally, or accidentally, you should never miss the opportunity to observe how different environmental factors or feeding regimens affect the growth and development of your fish. You do not need to use rigorous experimental techniques to learn and benefit from simple “accidental experiments”. For example, I would like to share with you my recent experiences with Azumanishiki fry. As compared to raising Ranchu fry, the Azumas are somewhat more difficult to cull and to raise successfully. First of all, being a calico variety, a full 50% of the fry will be either wild colored metallic or pinkie mattes, and these will need to be culled as soon as possible. The metallics aren’t too hard to spot, but it virtually impossible to distinguish between mattes and the very desirable blue base calicoes before they are around six weeks old or so. For this reason, it is necessary to keep many more fry for quite a bit longer before any meaningful selection can be accomplished.
Since Azumanishiki are technically a top view fish, I have experimented with raising them in shallow water, like I do with TVR fry. However, what I found was that the longer tail finnage of the Azumas becomes a real problem for them if the tail is too open or horizontal. The shallow water seems to favor more open and stiff tails, and they fry are soon struggling to lug around their big “jumbo jet” tails.
Given the fact that shallower water in aquariums also means less water volume, and less swimming space, it wasn’t entirely clear what role overcrowding, poor water quality, or lack of swimming space might be playing in the tail development. This year, I had lots of Azuma fry to work with, and I spread them out among 10, and 20L gallon tanks, and I also purchased a 5 foot round Kiddie Pool to raise a portion. Other variances were whether or not the tank bottoms were painted black, how much light each tank received, and whether there was a heater or filter (or just an airstone) in the tank. As the fry grew, I culled for the best color and tail/body shape and gave these fry what I considered the optimum care in heated aquariums. The others were released in the unheated kiddie pool on the garage floor, but were given good aeration and regular water changes. What I found was the aquarium-raised fry in the heated tanks were growing faster at first, but they soon exhibited signs of “disharmony” between their tails and their bodies. The tails began to tip up and the fish were swimming erratically. As the fish continued to eat and grow, they were often resting in the back corners of the tank and not swimming actively. The most affected fish were the very light colored, presumably matte, fish. However, I soon realized that none of the fish in the kiddie pool were having this problem. Also, the kiddie pool fish spent most of the day schooling and swimming around the circumference of the pool and their tails were softer and did not hamper the fishes’ ability to swim. Despite the relatively colder water, which ranged between (60F and 74F), the kiddie pool fry were still eating and growing well.
One last group of fry in a well-lit 20L aquarium with slightly green water also did exceptionally well. These fry were very well colored, and did not suffer from fin problems, which suggests that the either the better water quality (due to the algae) or some nutritional benefits from the algae may also be important factors.
Another observation was that the fish in the cleanest tanks with clear glass bottoms were not as colorful as the fish in either the kiddie pool (blue), or those with the painted (black) bottoms. I recalled the melanophore response to light in fish. This is much more pronounced in calico fish where individual melanophores can be seen against a light background. These melanophores increase in size to darken the fish against a darker background, which is very helpful when trying to distinguish between mattes and calicoes. This is similar to the way chameleons and squid change colors to camouflage.
The moral of the story is, when you must make the most of what limited resources you have, take the time to observe how these subtle environmental differences affect the development and condition or your fish. This knowledge will help you to better plan for your future spawns.