Laichzeitsteuerung bei Oreochromis niloticus (Pisces,Cichlidae) Untersuchungen zur Synchronisation von Laichfischbeständen in Kreislaufanlagen (English shop)

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Andreas Stamer’s dissertation “Laichzeitsteuerung bei Oreochromis niloticus (Pisces; Cichlidae) – Untersuchungen zur Synchronisation von Laichfischbeständen in Kreislaufanlagen” investigates methods for controlling reproductive timing and synchronizing Nile tilapia broodstock in intensive aquaculture systems. The research examines whether natural environmental parameters can be manipulated to achieve predictable spawning periods and enable the coordinated production of eggs and fry. Experimental investigations focus on the effects of water hardness, temperature, salinity, and pH on ovulation, spawning readiness, and egg quality. Changes in water temperature and acidity prove unsuitable for reliable synchronization, while variations in water hardness produce partially increased synchronization rates but insufficient egg quality and poor reproducibility. The most promising results are obtained through controlled salinity treatments combined with individual housing of broodfish. Under these conditions, reproducible spawning synchronization rates exceeding 70 percent are achieved within seven days, reaching a maximum of 83.3 percent. Shortening the duration of salt exposure improves egg quality, although reproductive performance remains below that of untreated control groups. Additional experiments compare different tilapia populations and genetically identical individuals to assess variation in reproductive responses. The findings demonstrate the potential of salinity-based spawning synchronization while identifying limitations that require further optimization for practical aquaculture applications.