Koi are the most popular choice of fish for backyard ponds today; however, there are several other types of fish that are also used for this purpose. Among these are goldfish, golden orfe, mosquito fish, bitterlings, mollies, minnows, game fish, trout and catfish.

• Goldfish are the easiest fish to keep in a backyard pond and, as a member of the carp family, they can vary in color from light yellow to red. Their diet consists of mosquito larvae and most varieties of goldfish do not outgrow the pond they reside in. Goldfish also breed easily and the fry are generally black in color and turn gold if the conditions are right. Types of goldfish, such as the shubunkin and the comet, have elegant flowing fins and vary in colors and patterns. In water gardens that are well planted, these fish may be able to survive without additional feeding. As a general rule for stocking goldfish, please allow 10 gallons for each fish.
• Golden Orfes require plenty of oxygen and should not be placed in smaller ponds or ponds without pumps. They are bottom feeding scavengers that can share a pond with koi or goldfish. Golden orfes often put koi and goldfish at ease while encouraging them to spend more time near the surface of the pond. Golden orfes are quick and playful and grow to be around 1.5 feet long.
• Mosquito Fish are excellent in controlling mosquitoes in your backyard pond. Being in the same family as the common guppy, the mosquito fish has a long, pale slender body with a tail that is moderate in size without coloration. These fish require a pond that is at least 20 gallons with plenty of plants so they can hide. Mosquito fish can also tolerate cold weather as long is the pond is deep enough and if it is aerated through the wintertime. The diet of these fish consists of the larvae of mosquitoes and other insects. You may have to supplement their diet with quality flake food if the amount if natural food is insufficient. If left to fend for themselves without a breeding box, the adult mosquito fish may also eat their own fry.
• Bitterlings are an excellent choice for your backyard pond because they feed upon the parasites that infect koi as well as insect larvae. They are carp like in appearance, generally have bodies that are gold or silver in color with dorsal and anal fins highlighted in white. To house bitterlings, you need at least 30 gallons of water as well as plenty of rocks and plants for them to hide in.
• Mollies are considered active and peaceful fish that prefer to be kept with other peaceful fish. In the same family as the guppy, platy and swordtail, mollies are live bearers that breed easily and come in a wide variety of colors such as orange, black and green. These fish will eat some live plants, flake food, brine shrimp, spirulina flakes and Tetra Color bits. It is important that you give mollies plenty of swimming room with plenty of rocks and plants to hide in. These fish also prefer warmer water that can be kept in temperatures of 78-84 degrees Fahrenheit with a teaspoon of aquarium salt per 5 gallons of water.
• Minnows are also great for eating algae, insect larvae and mosquitos and can survive a wide range of temperatures. The name minnow is a common one for the Cyprinidae, a family of freshwater fish that include 300 American species of carp. Even though most are dull in color, some minnows are hued in greens, yellows and reds.
• Game fish, such as the catfish and the trout, can also be kept in your backyard pond. However, these fish may be banned in some areas, so it is important that you check with your fish and game department before you consider adding game fish to your pond. These fish also require a very large pond to provide plenty of room.