We often get asked should I buy koi or goldfish for my pond. While both are great fish here are a few tips to figuring out which species you should have in your pond.
Goldfish varieties: Comets, Sarassa Comets, Fantails, Calico Fantails, Sarrassa Fantails and Shubunkins,
Positives: Goldfish are great for water garden environments, since they do not tear apart the plants like koi do at times. You can get great color options, fancy tails, and have more fish. We recommend 1inch of goldfish per 10gallons of water. Goldfish are also more affordable. The pond only needs to be 18″ deep.
Negatives: Goldfish will only grow to about 8-12inches. They tend to over populate, so you will have to thin the herd.
Koi and Butterfly Koi
Positives: They come in a variety of vibrant colors, get larger than goldfish, and sometimes will eat algae from the bottom of the pond. Koi do a better job keeping the population down by eating eggs and fry. They are more aggressive when it comes to feeding time which is fun to watch.
Negatives: Koi tend to dig up plants and eat the leaves. They are related to carp which are bottom feeders. Sometimes you get lucky and will have koi that are not interested in the plants but all it takes is one “bad fish” to show the others and then your plants are destroyed. You need much more water for koi, we suggest 200gallons of water per full sized koi 14inches and up. (Just measuring the body not including the tail) Having a deeper section of the pond is a great way to get those extra gallons without having to expand the surface area it just means more digging. Koi need better filtration because they become larger and create more waste.
So if you are looking to have a water garden with lots of water lilies and plants stick with goldfish and if you want the big beautiful fish go with a Koi pond. Either species are great fish to have in your pond.