The Performance of Continuous Rotifer (Brachionus Plicatilis) Culture System for Ornamental Fish Production

Abstract

Rotifers are considered as one of the most important prey organisms in the culture of altricial fish larvae. However, high density rotifer culture is often problematic due to water quality problems which results in frequent crashes. In the present study, the performance of a small-scale, continuous system was evaluated for culturing rotifers, Brachionus plicatilis, using concentrated nonviable green algae, Nannochloropsis oculeataas feed in a 160 L tank for a period of 90 days. The system configuration was simple and major components consisted of a protein skimmer and a pure oxygen delivery system. Although egg ratio increased from 3% on day 1 to 21.8% and 39.3% on days 7 and 9, respectively, rotifer growth was slow at start up and resulted in fluctuations in total number of rotifers between days 19-41. Rotifer densities remained < 400 until day 51 but increased at higher rates reaching 900 individuals/mL on day 55, 1,620 on day 60 and 2,127 on day 70. Rotifer density reached a maximum of 2,188 individuals/mL on day 85. Once the rotifer density exceeded 1,500 individuals/mL (day 60), periodical harvesting (a total of 16 harvest events) produced a total of 369,920,000 rotifers corresponding to a daily production of 12,330,667 individuals/day during the next 30 days until the experiment was terminated at day 90. As a result of periodic harvesting, water makeup and continuous protein skimming, total settleable solids and NH 3 -N levels remained low and ranged between 4-22 mL/L and 0.4-2.2 mg/L, respectively. The authors' findings indicated that this inexpensive culture system can be successfully used for small-scale marine or freshwater ornamental fish production. Further work is required to minimize lag period at start-up and increase the production potential and yield by better management of suspended solids.

Determination of the Optimal Conditions for the Mass Culture of Large-Type Rotifers (Brachionus plicatilis) at Low Temperatures

“…Rotifers are important to feed zooplankton because their size and slow motility make them suitable starter feed for larval fish during early exogenous feeding [1]. Furthermore, rotifers are easily digested and absorbed by fish larvae and can be easily enriched and cultured en masse; therefore, they are most commonly used as live feed for larval fish and crustaceans during the early stages of life [2][3][4][5][6][7][8][9][10]. Rotifers can be generally categorized into three types based on their size: Brachionus plicatilis (250-300 µm), B. rotundiformis (160-220 µm), and B. rotundiformis ssp.…”