Introduction
Chub is an important gamefish in Hungary. There is a growing angling demand for this species (Borics et al. 2016). Several studies have already been carried out regarding the rearing of the chub larvae in a Recirculating Aquacultural System until the 30th day after hatching (Shiri Harzevili et al. 2003; Zarski et al. 2008; Crooks et al. 2013; Kupren et al. 2015). However, nowadays limited information is available on chub larvae rearing older than 30 days of age. Based on our previously experience, feeding with complete fish feed resulted high rate mortality and high rate of larval deformity compared to natural live food, for example Artemia nauplii (Bartucz 2020). One of the critical factors during rearing can be the lack of vitamin C (Berillis 2015). The study aimed to investigate the growth parameters on chub fries using different feeds.
Material and methods
The fries were reared for 28 days at a temperature of 25±0,5 °C and an oxygen level of 7,5±0,5 mg/L in Recirculating Aquacultural System (RAS). The lighting period was 12 h/day. Fish were stocked in with the capacity of 10 L tanks at a density of 10 individual/L. The effect of four different fish feed was examined in six repetition in each group. Fish were fed twice a day in a dosage of 2,5%/bodyweight.
Four different feeds were used:
- Artemia nauplii (A),
- Artemia nauplii with 1000 mg/kg Vitamin C (A+C),
- complete fish feed (Aller Infa EX GR 0,4 mm) (CF),
- complete fish feed (Aller Infa EX GR 0,4 mm) with 1000mg/kg Vitamin C (CF+C).
After 7 days of feed acclimatization period, wet body weight and standard length were recorded on the 0th, 14th and 28th days. Wet body weight and standard length were measured on 10 individuals/sampling occasion/tanks. Wet body weight was determined with a Mettler Toledo AB204-S analytical scale with an accuracy of ±1 mg. Standard length was measured with a Leica M205 FA type microscope and a Leica DFC 7000T camera mounted on it with an accuracy of ±1 mm. At the end of the experiment, the survival rate was determined.
Results
In wet body weight and standard length, no significant difference was observed as an effect of the addition of Vitamin C at any of the three measurements. On day 28, wet body weight and standard length were measured statistically verifiable higher in A (117±42 mg and 16±2 mm) and A+C (129±51 mg and 17±2 mm) groups than CF (107±54 mg and 15±2 mm) and CF+C (104±36 mg and 15±2 mm) groups. At the end of the experiment, similarly high survival rate was observed in all groups (A: 94,83%, A+C: 95,66%, CF: 94,33% and CF+C 94,83%).
Discussion and conclusion
We have successfully reared chub fry in a Recirculating Aquacultural System with artemia and a complete fish feed also. At the end of the experiment, between the two feed types, statistically verifiable higher wet body weight and standard length were recorded in the artemia groups, compared to the complete fish feed groups. The type of feed affected growth, but the addition of Vitamin C did not affect the offspring rearing period.
Acknowledgements
Our experiments were supported by the EFOP-3.6.3-VEKOP-16-2017-00008 project. The project is co-financed by the European Union and the European Social Fund. This research was supported by the Ministry of Innovation and Technology within the framework of the Thematic Excellence Programme 2020, Institutional Excellence Subprogramme (TKP2020-IKA-12).
References
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