String Algae Control – The Plecostomus

I’ve seldom had a problem with String Algae Control because I rely on a plecostomus or three to do my dirty work. They LOVE String algae and they can live in any water above 56 degrees. At 55 degrees, the just. flat. die.

Above 70 degrees they actively eat green algae to it’s roots and they grow like weeds.

String algae happens to be their absolute favorite of all time. Bar none. I used to roll it up on a stick and even bring it inside to the plecos I had in my fish tank.

In winter, in their overwinter trash can, they eat Zuchini, but let me back track.

Plecostomus for String Algae Control in ponds and tanks
Plecostomus for String Algae Control in ponds and tanks

So there’s this ugly tropical algae eater that actually LOVES algae and eats it CONSTANTLY day and night. I started using them 10 years ago. The ONLY string algae they can’t get is the stuff they can’t get, namely the waterfall.

I traditionally use two plecostomus. In large ponds like twelve THOUSAND gallons I buy two of the bigger ones. In ponds like 2 or 3 thousand gallons I use two of the small ones. Babies in the much smaller ponds…..

TWO? Why two?

Because it’s all you need. Try it, and call me a liar. Pundits who have NOT tried it already do.

Plecostomus for String Algae Control in ponds and tanks
Plecostomus for String Algae Control in ponds and tanks

By the end of any growing season on unlimited string algae the plecostomus will be over a foot long. And they die summarily at 55 degrees. Not 56, but 55.

The fish Lock is carrying is dead, having died in October water. (In Georgia we have warm October days and frigid nights)

A word of warning.

Plecostomus are aggressive in very small facilities. I personally would NOT recommend a pair of plecostomus in less than 600 gallons unless very small. Slow moving fish like Goldfish may pay a dear price if they are pinned and grated by the plecostomus for it’s delicious slime coat and scales.

string algae

At left, a Telescope goldfish that was rasped completely scaleless and died from its wounds from a small plecostomus in a 55 gallon aquarium.

I have only seen this ONCE in a very small tank with Koi, and only one Koi was affected. It would seem, Koi are faster and more wily than Goldfish.

Given a choice, the Plecostomus would eat our effortless string and carpet algae than chase around mobile food.

Dr Erik Johnson is a Marietta, Georgia Veterinarian with a practice in small animal medicine. He graduated from University of Georgia with his Doctorate in 1991. Dr Johnson is the author of several texts on Koi and Pond Fish Health and Disease as well as numerous articles on dog and cat health topics.