This document provides guidance on producing live food organisms for larviculture. It discusses selecting food that larvae can perceive, ingest and digest. Two natural food types are phytoplankton and zooplankton. Culturing phytoplankton involves maintaining, enriching and isolating unialgal cultures. Isolating single algal units uses a capillary pipette method. Zooplankton culturing focuses on Brachionus plicatilis, describing its taxonomy, morphology, food/feeding, and culture techniques like daily tank transfers.

1. GUIDE TO THE PRODUCTION
OF LIVE FOOD ORGANISMS

2. SELECTION OF FOOD
Criteria:
1.The food must be perceived
by the larvae.

3. 2. The size of food must be such
that it can be accommodated by
the mouth of the larvae.
3. The feed should have high
dietary value especially Highly
Unsaturated Fatty Acids (HUFA)
essential to the growth and survival
of the larvae.

4. 4. The feed can be easily produced
in large quantities.
5. The feed can be digested by the
larvae.

5. Types of Natural Food
Organisms
1. Phytoplankton
2. Zooplankton

6. PHYTOPLANKTON CULTURE

7. In larviculture, the phytoplankton
may serve any of the following
functions:
(1)provide nutrients via accidental
or active ingestion by the larvae;

8. (2) detoxify the larviculture
medium by assimilating or
neutralizing inhibitory material;
(3) improve the nutritional
value of secondary food
organisms such as zooplankton;

9. (4) secrete into the medium
metabolic products which
facilitate larval growth and/or
development

10. TYPES OF ALGAL CULTURES
•Maintenance cultures - natural
collections of algae kept in
culture vessels in the
laboratory; here, succession of
the previously less abundant
species over the dominant ones
may occur.

11. •Enrichment cultures - refer to
crude collections of algae or
other algal source materials
treated with specially selected
culture media which will favour
the rapid increase in number of
desired algal species.

12. •Unialgal cultures - refer to
populations consisting of a
single algal species, although
other micro-organisms may be
associated.

13. •Axenic culture - contains a
population of a single algal
species, all other living
organisms being absent.

14. SAMPLING/ISOLATION
TECHNIQUES
•Phytoplankton may be
collected by towing through the
water special plankton nets
made of fine silk bolting cloth
(180 meshes/inch2
).

15. •Sampling bottles should be
uncovered and illuminated
promptly upon reaching the
laboratory.

16. •Competition among species is
one of the main difficulties in
maintaining a mixed
population.

17. So, there is a need to obtain a
unialgal culture

18. Two conditions must be fulfilled
to obtain unialgal or pure
cultures:
(1)the relevant or desired
species must be isolated, and
(2) it must be induced to
multiply.

19. Types of Isolation
A. Biological Isolation
Biological isolation of algae
can be attained through
enrichment culture
methods.

20. B. Mechanical Isolation
Stein (1973) has described a
number of isolation methods,
the more popular of which
include the capillary pipette
method, streak-plating, and
isolating on agar.

21. 1.Capillary pipette method
This method uses an inverted
Petri dish top as an isolation
dish.

22. •place 10–15 drops of the
natural collection in the centre
of the dish
•place 6–8 drops of suitable
liquid medium in six positions
encircling the natural collection.
Each droplet is then assigned a
numerical code

23. •with the use of sterile capillary
pipette, transfer the desired
algal units from the natural
collection to one of the six
drops. Desired algal units are
located while looking through
an inverted microscope or a
stereomicroscope

24. •transfer a single algal unit
from the first drop to the
second drop
•repeat the process (moving
clockwise) until a single algal
unit is present in a drop of
liquid medium

25. •transfer the single algal unit to
a sterile tube containing liquid
culture medium.

26. GROWTH
•denotes the increase in
number beyond that present in
the original inoculum
•usually refers to changes in the
culture of cells rather than to
changes in an individual
organism.

27. Growth Phases
1.The lag phase - After the
addition of inoculum to a
culture medium the
population remains
temporarily unchanged

28. 2. The logarithmic or
exponential phase - The
cells here begin to divide
steadily at constant rate.
Given optimal conditions,
the growth rate is maximal
during this phase.

29. 3. The stationary phase- the
logarithmic phase of growth
gradually begins to taper off
after several hours (or days).
The population remains
more or less constant for a
time

30. 4. The phase of decline or death
- After the stationary phase,
the rate at which cells die is
faster than the rate of
reproduction of new cells.
Here the number of viable
cells decreases
geometrically

31. CONDITIONS AFFECTING
GROWTH
1.Illumination
2.Temperature
3.Culture Medium
4.Starter/Inoculum

32. ZOOPLANKTON CULTURE

33. Brachionus plicatilis Muller
A. Taxonomic position
Phylum Trochelminthes
Class Rotifera (Notatoria)
Order Monogononta
Suborder Ploima
Family Brachionidae
Subfamily Brachioninae
Genus Brachionus Pallas
Species plicatilis Muller

34. B. General Description of
Rotifers
Most rotifers are microscopic
aquatic animals. The body
shape is extremely variable
and is divided into three
parts: head, trunk, and foot.

35. C. Potential
The rotifer Brachionus
plicatilis is one of the most
important zooplankton
species presently utilized as
live food for various
cultivable marine animals.

36. D. Food and Feeding
Chlorella has probably been
the most popularly used algal
food for the culture of
Brachionus plicatilis
Other food may include
yeasts (bakers or marine)

37. E. Culture Techniques
1.Daily Tank Transfer Method
2.The “drain–off” system for
large tank outdoor culture
3.The feedback culture system

38. The “daily” tank–transfer method
Involves continuous subculture of
Brachionus using 0.5 m tanks.
The tanks are initially used for Chlorella
cultures.
When Chlorella density reaches about 10–
20 × 10 cells/ml inoculation of rotifers is
done then are harvested and transferred to
another tank. The process of transfer of