Zooplankton Culture
Dr. Craig Kasper, HCC Aquaculture Program
Last Time: What’s a LUX??
• A unit of illumination equal to the direct
illumination on a surface that is everywhere one
meter from a uniform point source of one candle
intensity or equal to one lumen per square meter
called also meter-candle
• a unit of illumination, equivalent to 0.0929 footcandle and equal to the illumination produced by
luminous flux of one lumen falling
perpendicularly on a surface one meter square.
Symbol: lx
Introduction
• Zooplankton is required as a first food for many cultured
fish; for others it contributes to faster growth and
higher survival.
Since larval fish don’t take up much space, 0.1-3 acre ponds will do nicely, if
you are outdoors. Indoor fry culture can be done in 250-1000 gallon tanks
in a recirculation system.
• Tiny fry eat tiny prey, but are preyed upon by many
creatures bigger than they are.
• Stock the right size fry and feed the right size
zooplankton! Yes, some zooplankton would try to eat
your fry.
First Feeding on Zooplankton
• Most fish fry eat three main types of zooplankton—
rotifers, copepods and cladocerans.
• For the tiniest fish fry, HSB or WB, small rotifers may be
the only zooplankton small enough to eat.
• If fry are too large, then they rotifers may not provide
enough nutrition.
• Copepod nauplii, which are just-hatched copepods, are
important first foods for larval fish, too.
Rotifers
Rotifers
• Rotifer (0.04 -2.5 mm long).
Sim. to microalgae.
• “Wheel organ” a ring of cilia
that “rotates” around the mouth
• Appear early, hatch from “resting eggs”
in the pond reproduced rapidly
(2-8 days post hatch).
• Asexual reproduction: need good conditions
• Sexual reproduction: poor pond conditions
(“resting” eggs produced)
Rotifers
Hexarthra, note the egg attached
to this female
Floscularia, tube building rotifer,
attaches to plant stems.
Rotifer Setup
• Sterilized water (whether salt or fresh)
• pH and temperature should = starter culture.
• Temperature is 20 - 30° C
• pH 8.0
• Start with at least 10-20 rotifers/ml (minimizes crashing)
• 1-2 feedings per day; continuous preferable.
Counting…
• Counts determine health*
Sedgwick-Rafter Cells with Grid
female rotifer w/eggs
*Healthy cultures of rotifers contain many egg bearing females and
very few males. An increase in the number of male rotifers, easily
identifiable by their smaller size, is an indicator of a stressed culture
(bad H20 quality).
Hatching Rotifers
• SW
“L” Type - Brachionus plicatilis 200-360μ
“S” Type - Brachionus rotundiformis 150-220μ
“SS” Type - Brachionus rotundiformis 70-160 μ
FW Brachionus rubens, Brachionus calciflorus
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Temperature: 30°C
pH: 7.2-9
Feed: Nannochloropsis (algae)
Feeding Rate: 15 ml of Nanno/10 million "L" type/day
Feeding Times/Day: Continuous, or every 3 hours
Artemia nauplii
“I must apply myself!!!”
Copepod Artemia nauplii
• Next copepods to appear from resting eggs.
• Artemia molt up to 12 times before reaching adult stages
(provides an increasing food size for larval fish.)
• Adults may reach 3 mm length
Hatching Requirements
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Good water.
Clean clean equipment, tubing hatching contianer, etc.
pH: 8.5
Illumination: constant bright light
Temperature: 24-28°
Aeration: needed to keep Artemia cysts circulating.
Salinity: recommended to be approximately 24-28ppt.
Density of cysts should not exceed 10 grams / liter.
Incubation Time: usually hatch out takes approximately
24 hours.
Cladocerans (Water Fleas)
• Cladocerans: third major group
• Larger fry and even adults eat them.
• Cladocerans 2 to 3mm long are commonly found in
culture ponds several weeks after the ponds are filled.
• Hatch from resting eggs.
• Cladocerans compete with rotifers and calanoid
copepods for phytoplankton.
Daphnia magna
Very large!
eggs
Life History
• D. magna live approx. 40 days at 25°C and
about 56 days at 20°C.
• Life History:
(1) egg
(2) juvenile
(3) adolescent
(4) adult
(Pennak, 1978)
Culture Parameters
• Salinity - 99% of Cladocerans are freshwater
• Oxygen - Tolerant of low oxygen. A slow aeration is needed.
Aggressive bubbles kill them (Bio-foam filters work great!)
• pH - 7.2 - 8.5.
• Hardness: D. magna tends to prefer harder water (170 mg
carbonate hardness) and D. pulex a little less hard (90 mg
carbonate hardness).
• Temperature: Daphnia magna 18-22°C (64-72°F)
D. pulex > 10°C.
Moina 5-31°C (41-88° F); opt. 24-31°C (75-88°F).
• Food: Green water, yeasts, bacteria
• Other facts: <0.5 ppm P stimulates reproduction, but concentrations
higher than 1.0 are lethal to the young.