The Impact of Carbon to Nitrogen Ratios on the Growth, Water Quality, and Color Quality of Koi Fish (Cyprinus rubrofuscus) in a Biofloc System Supplemented with Spirulina platensis

Dewi, Nina; Nindarwi, Daruti; Sari, Lutfiana Aprilianita; Fauzan, Agung

doi:10.21608/ejabf.2025.381221.5803

The Impact of Carbon to Nitrogen Ratios on the Growth, Water Quality, and Color Quality of Koi Fish (Cyprinus rubrofuscus) in a Biofloc System Supplemented with Spirulina platensis

Document Type : Original Article

Authors

¹ Department of Aquaculture, Faculty of Fisheries and Marine, Universitas Airlangga

² Department of Aquaculture, Faculty of Fisheries and Marine. University of Ailrangga.

³ Department of Aquaculture, Faculty of Food Security, Universitas Negeri Surabaya

10.21608/ejabf.2025.381221.5803

Abstract

Koi fish are freshwater ornamental fish that have high economic value. High koi fish production and good fish color quality are significant factors in the success of koi fish culture. The aim of this study was to evaluate the effect of different carbon to nitrogen ratios on the growth performance, water quality, and color quality of koi fish with Spirulina platensis enrichment. Four treatments and three replications were employed in this study's completely randomized design (CRD). The treatments used included control (K) without biofloc + Spirulina platensis 5% treatment, (P1) biofloc C/N ratio 12 + Spirulina platensis 5% treatment, (P2) biofloc ratio C/N 15 + Spirulina platensis 5% treatment, and (P3) biofloc C/N ratio 18 + Spirulina platensis 5% treatment. As many as 125 fish were reared in a tarpaulin pond and fed with artificial feed mixed with Spirulina plantesis powder three times a day with a feeding rate of 5%. Parameters observed included specific growth rate, feed conversion ratio, feed efficiency, survival rate, fish biomass, the color quality of koi fish, and water quality. The outcomes revealed that the P3 treatment had the highest specific growth rate, survival rate, feed efficiency, fish biomass, and color quality but the lowest feed conversion ratio value among control and other treatments. In addition, application of biofloc technology can decrease ammonia, nitrate, and nitrite parameter in the culture ponds so that it can provide clean water for koi fish.

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