"Neutered carp" if you mean grass carp aka white amur (triploid sterile), then these fish are completely different from the common carp & varieties complex. Different in species name and even the next higher group type name - genus - technical name being Ctenopharyngodon idella. Grass carp (GC) are very different in many ways from common carp Cyprinus carpio. Different in general behavior, feeding behavior, reproductive behavior, digestive tract structure, fin type and position, scale shape & structure, mouth shape, structure, and function to name a few.
As far as pond owners are concerned, grass carp are primarily herbaceous fish (vegetarians) preferring to eat plants and the most tasty, tender ones are eaten first similar to you at the salad bar, whereas the common carp group prefer to eat primarily animal invertebrates that they suck and filter out of the sediments and the few ingested plant materials consumed are secondary and probably mostly incidental in the diet; all depending on what is present in the habitat.
IMO in ponds with little competition from the same specie of fish (only a few are present), the common carp eat mostly the abundant ungrazed invertebrates that inhabit the bottom sediments/muds and the carp's frequent feeding activity of stirring & roiling the sediments keeps plant growth stressed to the point that problematic plants gradually become less of an apparent or visible problem. In a scientific study of the feeding habits of common carp and Israeli carp, the bottom of freshly drained ponds contained abundant pock marks or divots where the carp and been aggressively feeding in the sediment. FYI common carp do not have a stomach, thus they can not binge feed like bass and bluegill filling the stomach and then waiting numerous hours or a day or two before eating again. Common carp and close relatives feed frequently to keep food moving through the digestive tract. However, in almost all cases the less plant growths are due to suspended sediment solids as murky water with less light penetration and less resulting phytoplankton. Phytoplankton do not grow well when lots of suspended microscopic sediments are in the water column.
Just because your water is less transparent or clear does not mean phytoplankton are creating a beneficial bloom. When in many cases if the truth were known, pond water cloudiness is in reality tiny size microscopic dirt (detritus) not phytoplankton. FYI - generally if the cloudy water has a grennish hue then it is primarily phytoplankton whereas if the hue is brownish, tan, or the light shade of the color of your soils, then cloudiness is mostly due to suspended detritus not beneficial phytoplankton.
Last edited by Bill Cody; 12/10/13 04:21 PM.
