THESIS INFORMATION
Thesis title:
Specialization:
Study on the biological characteristics, culture and use of freshwater
rotifer (Brachionus angularis)
Freshwater Aquaculture
Training field Code: 62 62 60 01
Student:
Tran Suong Ngoc
Supervisors:
A/Prof. Dr. Vu Ngoc Ut, Can Tho University
A/Prof. Dr. Truong Quoc Phu, Can Tho University
Training institution: Can Tho University
I.
THESIS SUMMARY
Study on the biological and reproductive characteristics of freshwater rotifer
Brachionus angularis with the aim to evaluate its potential in different natural habitats.
And based on these characteristics a culture protocol (procedure) has been made for
freshwater rotifer Brachionus angularis, which will contribute to the hatchery phases of
target fresh- or brackish species recently. Thesis has covered (1) distribution of fresh water
rotifer B angularis in different eco-systems (e.g. run-off, static, fresh-water, brackish water
and acidic waters), (2) biological characteristics included of embryo development,
maturation, fecundity, brood-interval, life-span…in correspondent temperature, pH and
salinity; (3) feeding strategy (Chlorella and yeast), initial stocking density (200, 300, 400
and 500 ind./mL), water exchange (10%, 20% và 30%/day), biomass collecting rate (15%,
25% và 35%/day), culture parameters (temperature, pH and salinity) on the fresh water
rotifer B. angularis with the aim to develop a culture procedure for optimal biomass
production; and (4) application of freshwater rotifer B. angularis in nursery of Sand goby
or Marbled sleeper (Oxyeleotris marmoratus Bleeker) (optimal feeding level and culture
procedure with and without green-water system) in order to improve their survival during
day 1-10.
II.
NEW FINDING OF THE THESIS
The freshwater rotifer Brachionus angularis (isolated in the Mekong Delta, South of
Vietnam) could distribute at very low pH (≤4) and brackish water (up to 5 ppt) in the
estuaries, this except unique character could not find in the other strain of B. Angularis in
the world, and thus they are suitable in mass culture for initial feeding to a number of
fresh- and/or brackish water species in the Mekong Delta.
Compared to the other strains, B. Angularis on this study shows its tiny size and
quick reproduction, high fecundity and fast population development, which are feasible in
biomass production for feeding to early stages of fries, especially those characterized with
too small mouth dimension.
Application of B. Angularis in nursery of Sand goby (or Marble slepper) Oxyeleotris
marmoratus Bleeker during day 0-10 helped to improved considerably their survival
compared to the traditional feed (yolk and soya flour) from 19,3 % to 43,6%, respectively.
This proved significantly that feeding strategy has to meet not only nutritional level but
appropriate feed particle is crucial. Moreover, acclimatization of B. Angularis up to 5 ppt
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(or even higher) to bring up a possibility of mass culture of this species to fulfill the live
feed requirement of valuable species in aquaculture.
III.
APPLIED FINDINGS AND FUTHER RESEARCH NEEDS
3.1. Applicable possibility of thesis’s out-come
Finding and completion of basic knowledge on biological and reproductive
characteristics of freshwater rotifer B. angularis for lecture note and further investigation
for production of this valuable live-feed.
Culture and application of live-feed B. angularis in the hatcheries of target species
(Giant gourami, Discus fish) will improve their survival and cost effective in production of
these species in aquaculture.
3.2. Further researches necessary
- Acclimatization to salinity higher than 5 ppt to fill-up a high demand of (small)
rotifer in marine species hatcheries is expected.
- Scaling-up and modified culture protocol for appropriate culture volume may
needed
- Application of B. Angularis to other valuable freshwater species should be
considered.
Supervisors
A/Prof. Dr. Vu Ngoc Ut
Student
A/Prof. Dr. Truong Quoc Phu
CERTIFIED BY TRAINING INSTITUTION
RECTOR
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Tran Suong Ngoc
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