| A two year study on the effects of supplemental stocking of koi into bluegill nursery ponds was conducted at American Sportfish Hatchery in Montgomery, Alabama. Fingerling koi (∼10 cm in length) were stocked into the nursery ponds after bluegill reproduction was confirmed in the ponds. In year 1 of the study, 250 koi per ha were added to the bluegill nursery pond. In year 2, 500 koi/ha were stocked into the nursery ponds.; The addition of koi to nursery ponds had a significant effect on the water quality. In the first year of the study the presence of koi reduced the concentrations of total phosphorus, total nitrogen, and chlorophyll a in the ponds. The addition of koi had little effect on the total harvest of fish from the ponds.; In the second year of the study, with a stocking rate of 500 koi/ha, the presence of koi enhanced many of the key water quality parameters. Concentrations of total phosphorus, total nitrogen, total suspended solids, total ammonia nitrogen, turbidity and primary productivity were all significantly higher in these ponds. Conversely the bluegill harvest in these ponds was significantly reduced. |
