Fish ponds require more care and work than regular garden ponds. However, the calming effect that a fish pond will lend to your backyard will be worth all of its maintenance and cost combined. Orange and white Koi are the most popular type of fish for garden ponds because they are fairly visible underwater. Fish ponds will require a few very important pieces of equipment such as a pond thermometer, a heater, a de-icer and a pond aerator. Pond thermometers ensure the pond temperature remains around 59 degrees Fahrenheit. A pond heater or de-icer will keep ice from forming across the pond's surface. An aerator provides oxygen and helps break down organic matter.