Garden Pond Scavenging Fish: Green Tench and Golden Tench
Most pool owners want at least a couple of scavengingin their pool, for these will clear up uneaten goldfish food and also dispose of gnat larvae and other undesirable creatures. Unfortunately, many newcomers believe that scavenging fish will be the magical cure that will ensure clear water, devouring green suspended algae and blanket-weed as well as all the mulm that naturally occurs on a pool floor. This popular misconception is unfortunate, for it tends to lead the pool owner to believe that the pool can be left to its own devices once stocked, and that the scavengers will take care of any problems that arise. They then tend to be lazy about maintaining a natural balance of plant life which is really the magical cure.
Green tench are the most popular scavenging fish. These have short broad bodies and distinctive tapering heads. In common with all the other so-called scavengers, they inhabit the murky depths of the pool and are only rarely seen. Therefore, little would seem to be gained by introducing its orange-yellow variety, the golden tench, an often recommended addition or substitute for the ordinary green kind. As this is quite an expensive character and seldom visible its use should be restricted to the coldwater aquarium.
The same might be said for the various coldwater catfish, for although they have been traditionally sold as scavenging fish, they are really not suitable. There are three different hardy catfish sold by dealers in this country. The horned pout, the brown bullhead and the German wels or wailer. All look superficially alike, with slender, slippery, grey, black or brown bodies, broad heads and long barbels or whiskers. In their juvenile stage there may be something to be said for including them, for they feed voraciously upon all manner of aquatic insect life. However, as they mature their tastes alter and they then prey upon fry and other small fishes.