Welcome to PB. I am not sure how , if at all , this effects what you are testing but tilapia are mouth brooders and I have no idea what happens if the parents are not there. Maybe nothing. If you are trying to see if it hatches in space and how the fry do timing will be critical. You could put them in a hatchery clear plastic bag infused with O2. Development and hatching are controlled by time , water temp and light. Egg diameter varies within a species partly upon the parents condition. Egg size can vary among species as well. A good general size is 1.4 to 4 mm in dia.
General info
https://srac.tamu.edu/index.cfm/event/getFactSheet/whichfactsheet/53/https://srac.tamu.edu/index.cfm/event/CategoryDetails/whichcategory/11/ More
The Progressive Fish-Culturist 56:58-59, 1994
© Copyright by the American Fisheries Society 1994
A Simplified Method for the Controlled Production and
Artificial Incubation of Oreochromis Eggs and Fry
GEORGE B. BROOKS, JR.'
Center for Marine Studies, San Diego State University
San Diego, California 92182. USA
Abstract. —This paper describes a simplified technique
for the artificial incubation of the eggs of Oreochromis,
which require constant motion during incubation. A
central tube serves as an airlift pump, providing a gentle
flow of water.
For the aquaculture industry to grow in Arizona,
a simple inexpensive method of producing tilapia
fry is needed. Tilapias of the genus
Oreochromis2 keep their eggs in constant motion
as part of mouth incubation. Any technique for
artificially incubating the eggs or larvae must imitate
this process. Most incubation techniques for
eggs of mouth-brooding tilapias are complex
(Rothbard and Pruginin 1975; Rothbard and Hulata
1980). The following is a description of a simplified
technique for artificial incubation of Oreochromis
eggs.
Two breeding groups, each consisting of a single
1 Present address: Arizona Cooperative Fish and
Wildlife Research Unit, 210 Biological Sciences East,
The University of Arizona, Tucson, Arizona 85721,
USA.
2 The American Fisheries Society's preferred name
for this genus is Tilapia.
adult male and three adult female Oreochromis
tilapias, were placed in two 300-L rectangular tanks
of fresh water (Rothbard and Pruginin 1975;
Brooks 1990). Water quality was monitored daily
and maintained by the use of undergravel filters.
Once every 7 d, the oral cavities of the females
were checked for eggs or sac fry. Eggs or sac fry
found were washed into a petri dish and counted.
The eggs or sac fry were maintained in a partially
submerged fry net (15.25 cm wide x 12.7
cm long x 8.9 cm deep), suspended in a 15-L
cylindrical plastic container (Figure 1). The 250-
Mm-mesh prevented the loss of eggs or sac fry while
allowing water passage. Water temperature was
maintained at 26 ± 2°C by placing the incubator
in an external water bath. The eggs were agitated
by water pumped from a simple airlift device made
from schedule 40 polyvinyl chloride plastic pipe
and fittings (12.7 mm diameter). The central tube
served as an airlift pump. The extra length of open
pipe above the unit allowed the release of compressed
air and prevented spurting from the water
pipe. The result was a gentle flow of water that
kept the eggs or sac fry in constant motion. The
water flow was adjusted by increasing or decreasing
the air supply with a three-way valve. Gravel
AIR DUMP
WATER DUMP
NET
TOP
BASE
AIRLINE
BASE
FIGURE 1.—Culture apparatus for Oreochromis larvae, showing details of operation.
58
TECHNICAL NOTES 59
at the bottom of the apparatus anchored the airlift
pump and provided effective filtration.
Egg survival to hatching varied from 70 to 90%
and averaged 81%. Between 20 and 90% of the fry
survived to yolk-sac absorption (mean survival,
60%). Flowing water kept the eggs in the water
column and avoided trapping them in creases or
folds in the net. Eggs that were not in motion were
quickly killed by fungus.
The newly hatched sac fry required a strong water
flow to keep them in the water column. Progressively
less flow was needed as they matured.
The tumbling motion and contact with the net did
not damage the fry. The time required for yolksac
absorption was not uniform. Therefore, after
they hatched, the fry were fed periodically (twice
daily) all they could eat of Tetra Min, Baby Fish
Food "E" (liquified). During feeding, the water
flow was temporarily stopped to retain the feed
within the net. Use of the liquified fish food prevented
any build up of uneaten food near the fry.
Acknowledgments. —This project was funded by
the San Diego State University Center for Marine
Studies and the University of Arizona Maricopa
Agricultural Center. Invaluable support was provided
by Richard Ford and Stuart Hurlbert.
Thanks for assistance, equipment, and facilities
go to Patty Ancinec, Jim Zimmer, Bob Magnin,
and Robert Smidt. A special thanks goes to Eugene
Maughan for reviewing the manuscript.
References
Brooks, G. B., Jr. 1990. The effects of salinity and food
type on larval development, growth, and oxygen
consumption of the hybrid golden tilapia Oreo
chromis mossambicus * Oreochromis urolepis hornorum.
Master's thesis. San Diego State University,
San Diego, California.
Rothbard, S., and G. Hulata. 1980. Closed-system incubator
for cichlid eggs. Progressive Fish-Culturist
42:203-204.
Rothbard, S., and Y. Pruginin. 1975. Induced spawning
and artificial incubation of Tilapia eggs. Aquaculture
5:315-321.
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