Pond Depth
Pond depth should be a minimum of 15" to 18" for goldfish and 24" for koi. Ideally, you should have a section 2.5' to 3.0' deep for koi.
Co-habitation
Koi and goldfish co-exist very well together. However, they can interbreed which may be a drawback for koi enthusiasts.
Quantity of Fish
The general rule of thumb is 1" of fish per 10 gallons of water. However, with adequate aeration and filtration, you can double this to 2" of fish per 10 gallons of water. An average size waterfall usually produces plenty of aeration.
Feeding Your Fish
Goldfish are quite self sufficient feeding on algae and other plant material. But if you want to ensure good growth and color, feed once a day with a high quality gold fish food. Feed the amount they will finish in five minutes. Koi, on the other hand, must be fed daily due to the fact that they don't have stomachs and cannot store food. It is best to feed koi once or twice a day (all they will finish in 5 minutes), but do not over-feed them! During warmer months (when water temperatures are above 65°F), a high protein food will enhance color and growth. As the water gets cooler, it is a good idea to switch to a food lower in protein and higher in wheat germ. During colder months (when water temperatures are below 50°F) the metabolism of koi slows down and they no longer need to be fed. Any koi food is also fine for goldfish.
Do Fish Eat Plants?
Fish sometimes eat plants, however, this is much more likely to be the case with large koi and hard to predict. Many pond owners have koi and plants living in perfect harmony, while others are fighting a constant battle.
Extreme Water Temperatures
Cooler temperatures for fish are fine, so heating your pond is not necessary. The only threat from extreme cold is if the pond freezes solid.
However, it is very important to protect fish from rising water temperatures from our hot Central Texas summers. Providing adequate depth (18" for goldfish and 24" minimum for koi) and sufficient plant coverage for shade (60% - 70% surface coverage,) will allow more oxygen in the water for your fish. Fish need adequate oxygen to survive and warm water does not retain dissolved oxygen as well as cooler water. Oxygen is provided by plants photosynthesizing during the day, but only by your water feature at night. So don't turn off your waterfall at night. This is a common mistake that can be detrimental to fish.
Transporting Fish
- After purchasing your fish, be sure to keep them cool during the trip home. Never leave fish in the car during warm weather.
- Allow your fish to adjust to the water temperature of your pond. Do this by floating them on your pond in the bag of water they are transported in for about thirty minutes before putting them directly into the pond.
- When fish are transferred from one place to another, they can become stressed, so don't be surprised if your fish do not eat for a few days.
- Make sure that your pond water is dechlorinated before adding fish. This is done with dechlorinating agents or by filling your pond and waiting at least ten days. Cedar Park and Leander residents should be aware that the tap water may contain ammonia levels that are potentially deadly for fish. In this case, you need to use a dechlorinator that also binds ammonia, such as Ammo-Lock, Kent Detox or Vanish.
