1st ?. I do not currently have GC but have used them in my two previous pond managements. I had two GC in a 1/3 ac pond that I drained this spring. I have recommended local people use GC in numerous weedy pond situations. Most people stock too many in trying to eradicate pond weeds. Pondweeds are beneficial, some weeds are more benefit that others, similar to fish and people. Many people make the mistake of stocking number of GC per surface acre as opposed to number of GC per VEGETATED acre of water.
2nd ?. I am pro grass carp in the correct or proper situation.
Thoughts - Experiences.
1. Too many GC per acre are bad and denude the pond and then contribute to extra turbidity.
2. The type or specie of weeds has a big affect on how much weed growth each fish will eat. Fewer fish will control tasty weeds whereas more fish are required to control non palatable weeds. Some weed are more palatable than others. GC by eating all the good tasting weeds, can actually contribute to establishment of a unpalatable and different type of weed in some ponds.
3. I am convinced that some grass carp have different tastes for weeds (individuality). Sometimes 3 GC will provide effective control whereas 3 different fish in a different & same sized pond will not control the same specie of weed. Go figure.
4. I currently do not have them because I am able to manually remove and adequately manage the vegetation. Most of my current underwater pond vegetation is planted / introduced and management is feasable. Certain types of water weeds spread slower, are less intrusive, easier to manually control, and are more fish & angler friendly.
5. For ponds 1 ac or less with a weed problem, I recommend the owner remove as much vegetation as posible / feasable. When it gets uncontrollable, the owner should try to remove 25% of weeds, stock enough GC to eat 25%-35% of the weeds and leave the remaining 40% to 50% of the weeds for fish habitat and competition against filamentous algae. Very Often when all the vegetation is removed, it is replaced in volume by filamentous algae. Nature demands that some type of plant utilize the available nutrients. More nutrients accumulate each year in a pond. The type of pond watershed and the management methods determine how many nutrients each pond obtains each year. Shallow ponds (less then 8ft deep)are problematic for weed growth.
