A small team of carefully selected algae eating fish can contribute happily to your goal of keeping a pristine pond. Of course, this special team can’t manage it all themselves. You’ll still need to provide circulation and aeration with a pond pump and aerator, and filtration is important for maintaining your water chemistry. Then there’s the higher level maintenance, like removing dead leaves, rogue volleyballs, or other detritus that may fall into your pond. Keep in mind that while algae eaters will relish both string algae and the kind that coats rocks and the sides of your pond, they will not eat the single celled algae that makes your water green, or any of the deadly varieties like blue-green algae.
It may come as a surprise, but koi are actually dependable algae eaters, although it’s not their favorite food and they’ll always choose a few bits of sweet potato or rice over grazing for algae, so make sure that you err on the side of underfeeding to encourage your koi to browse. The common pleco is well known as an algae aficionado, and it can thrive in a pond with other fish, although it generally prefers to be the only pleco in the roost. Channel catfish are also dependable algae eaters, and as scavengers and omnivores, their services can keep a lot of waste from building up in the bottom of your pond. However, they can sometimes be aggressive, and can grow to be quite large. Another particularly fascinating candidate is the mild mannered Chinese Hi Fin Banded Shark, but these fish can reach over 4’ as adults and should only be considered if your pond is quite large. If your pond fits, though, what could be better than a friendly shark? A particularly good candidate for smaller ponds is the Otocinclus Catfish, which many consider to be the best algae eater of all. Small in stature, gentle in demeanor and delicate mannered while eating, they won’t disturb plants and they are voracious algae eaters. Keep in mind, though -- they’ll need to overwinter indoors.
