Theses and Dissertations

Title: Fishes as bio-filters for the improvement of pond water quality

Name: Kilgen, Ronald Henry

Degree: PhD

Chair: Dr. H.S. Swingle

Resides: FAA Library

University: Auburn

Location: Auburn, Alabama

Date: 1969

Pages: 122

Keywords: Fishes,Biofilters,Water Quality.


The effects upon the standing crop of mixed-stocking of channel catfish, Ictalurus punctatus (Rafinesque) with goldfish, Carassius auratus (Linnaeus), and with Tilapia aurea (Steindachner) were evaluated, along with the effects of recirculating water between connected ponds. The experiments were conducted in 0.002-ha concrete ponds. In single pond tests catfish were stocked alone or in combination with a bio-filter species in the same pond. The catfish plus tilapia stocking yielded 6,302 kg/ha more than did catfish stocked alone. In double pond tests the water was circulated from ponds containing the bio-filter species and back to the catfish ponds. Circulation was accomplished by air-lift from one pond to another, with return by gravity. Catfish plus tilapia stocked together in both ponds of the recirculation system yielded 9,842 kg/ha more than catfish stocked alone in a recirculation system. Food conversion for the catfish in the best treatment was 1.5, with 90 per cent survival. Tilapia added up to 3,800 kg/ha to the carrying capacity of ponds when stocked with catfish. Since they fed mainly on wastes and plankton, the only cost for the added production was the price of the fingerling tilapia. Dissolved oxygen was the main limiting factor for high fish production. Other water quality parameters did not approach lethal levels. Catfish survived 0.2 ppm dissolved oxygen for short periods: goldfish and tilapia were not noticeably affected by low concentrations.

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