Characteristics of a commercially produced larval feed and
its potential use in the mass culture of marine fish larvae
Edward Chesney and Emily Speir
Louisiana Universities Marine Consortium
Chauvin, LA 70344 USA
Most marine fish larvae need to consume live
prey at first feeding to grow and survive
Live Feed Challenges
• High costs and labor intensive to produce or buy
• Potential culture crashes can happen at critical
times
• Sub-optimum nutrition w/o enrichment strategies
• Limited size range of zooplankton (rotifers and
Artemia) cultured for mass production
Zooplankton sizes
700
Acartia
Temora
Paracalanus
Centropages
Undinula
600
Prey Width (um)
500
400
300
Artemia nauplii
200
Rotifer
100
0
N1
N2
N3
N4
N5
N6
C1
Stage
C2
C3
C4
C5
A
Product designed for shrimp culture
Liquid suspension:
• Designed to provide
balanced nutrition and
meet larval food
requirements
Designed as a supplement to
live feed strategies
Potential advantages of a liquid feed supplement
• Micro-particle sizes can be optimized for ingestion
by a particular size or type of larvae
• Encapsulated liquid food particles hold their shape
once immersed in seawater
• Particle integrity reduces water quality problems
and increases probability of ingestion with
nutritive value intact
• Use of the liquid food may improve survival when
transitioning to dry feeds
Cargill Liqualife™
• Product comes in three size ranges
• Z-M
• M-PL
• PL
-8
-6
-4
-2
0
0
0
1
91 0
-1
11 00
11
1 3 20
11
1 5 40
11
1 7 60
11
1 9 80
12
2 1 00
12
2 3 20
12
2 5 40
126
0
71
51
31
11
0-
F re q u e n c y
Size of Liqualife™ Z-M
80
70
60
50
40
30
20
10
0
Length
Width
Particle dimensions (microns)
12 80
114
18 0
120
24 0
126
30 0
132
36 0
138
42 0
144
48 0
150
54 0
156
60 0
162
66 0
168
72 0
174
78 0
180
84 0
186
90 0
192
96 0
198
0
61
020
Frequency
Liqualife™ M-PL
Particle size s fo r M -PL Liq u ilife
70
60
50
40
Length
W idth
30
20
10
0
S iz e (um )
Liqualife™ Particles
Liqualife™ suspends easily in seawater
Important to understand how long it stays suspended!
•Fish larvae look out and
up when they feed
•They swallow prey
whole
EXPERIMENT I
Objective:
Observe effects of aeration on liqualife™ particle
settlement
•
•
•
•
•
Four salinities (0, 10, 20, 30 ppt)
Two replicates/treatment
2 L volume
Suspended ~7000 particles/L
Treatments: with and without aeration
Experiment I-W/O Aeration
LiquaLife Average Density Over Time
Trial 2
LiquaLife Average Density Over Time
Trial 1
14
12
8
Density (particles/mL)
Density (particles/mL)
10
0 ppt
10 ppt
20 ppt
30 ppt
12
0 ppt
10 ppt
20 ppt
30 ppt
6
4
2
10
8
6
4
2
0
0
0
1
2
3
Time (Hours)
4
5
6
7
0
1
2
3
Time (Hours)
4
5
6
7
Small-Scale Aeration Trial
18
Density (particles/mL)
16
14
12
10
8
6
0
Hours
Hours
Hours
Hours
1
vs
vs
vs
vs
0 ppt
10 ppt
20 ppt
30 ppt
2
3
Time (Hours)
4
5
6
7
Medium Scale Liqualife™ Suspension Trials
• Particles delivered by an
automatic feeder.
• Delivered Liqualife at
two rates (125 and 250
suspended particles per
mL in feeders).
• Sampled near (back) and
away (front) from where
the feed was delivered to
the tank to look for
effects on distribution.
Distribution of Particle Suspension-80 L tanks
Particles p er mL
Mean Number of Particles
15.00
10.00
5.00
0.00
High-front High-back low-front
low-back
Concentration
• Found no significant difference.
Effect of Aeration and Time on LL Particle
Suspension
18
16
T im e (h rs) v s N o A ir
T im e (h rs) v s M e d iu m A ir
T im e (h rs) v s H ig h A ir
14
12
Particles per mL
Treatments:
• Three levels of aeration by
an airstone (no air, medium
and high air).
• Particles delivered by
feeders.
• No significant difference
on the rate of particle
settlement over time.
10
8
6
4
2
0
0
2
4
6
T im e (h rs)
8
10
12
14
Effect of Particle Size on Settlement Rates
• Suspended Liqualife™ at 125 per ml in 500 mls of
seawater
• Replicate samples were collected in replicate tanks
at one hour after the feeder began, when the
feeders ran out then at one and two hour intervals
after the feeder was empty.
• The length and width of fifty particles were
measured in each sample.
Negligible difference in the suspension of smaller vs larger particles
One Hour After Feeder Began
Feeder Empty
25
20
Tank 1-W
15
Tank 8-L
10
Tank 8-W
5
20
Tank 1-W
15
Tank 8-L
10
Tank 8-W
5
0
Size Range
200-220
180-200
160-180
140-160
Size Range
One Hour After Feeder Emptied
Two Hours After Feeder Empty
25
20
Tank 1-L
15
Tank 1-W
10
Tank 8-L
Tank 8-W
5
0
Frequency
25
Tank 1-L
20
Tank 1-W
15
Tank 8-L
10
Tank 8-W
5
Size Range
Size Range
200-220
180-200
160-180
140-160
120-140
100-120
80-100
60-80
40-60
20-40
0-20
0
020
20
-4
0
40
-6
0
60
-8
80 0
-1
10 00
01
12 20
01
14 40
01
16 60
01
18 80
02
20 00
022
0
Frequency
120-140
100-120
80-100
60-80
40-60
20-40
0-20
20
022
0
16
018
0
12
014
0
80
-1
00
0
40
-6
0
020
Tank 1-L
Tank 1-L
Frequency
Frequency
25
Preliminary Red Drum Trial
• Design: red drum larvae grown to 7 DAH and then
restocked into two treatment
• Treatments: rotifers only (2000 . L-1) and rotifers
with Liqualife particles suspended in seawater and
added throughout the day by automatic feeder
• Mean Temp= 25.8; Salinity ~ 32 psu; Ammonia
checked daily and maintained below 0.5 ppm
• 1 liter of Isochrysis galbana added to each tank
daily
• Larvae were grown to 13 DAH and sacrificed
Preliminary Red Drum Results
Mean final length
@ 13 DAH
Growth Rate
Survival
Rotifers With
LiqualifeTM
Rotifers Only
9. 41± 1.21
mm TL
0.64 mm . d-1
93%
8.39± 2.31
mm TL
0.54 mm . d-1
73%
Experiment II Design
• Four replicated treatments
setup in recirculating culture
system.
• The aeration in each tank was
set to about 50mL per minute
and the flow rate was set to
turn over the water about 1.5
times a day.
• The feeders dispensed
Liqualife™ every 5.5
minutes.
Pompano Trial
Design: pompano larvae stocked at 2 DAH into four
treatments. All treatments offered zooplankton at first
feeding.
At 4 dah treatments were:
1)wild zooplankton only (2000 per L-1)
2)1 ml Liqualife™ suspended in 1L seawater
3)½ ml Liqualife™ in 1 L SW plus zooplankton
4)1 ml Liqualife™ in 1 L SW plus zooplankton
•Mean Temp=26C Salinity ~ 32 psu
•1 liter of Isochrysis galbana added to each tank daily
•Larvae were grown to 12 DAH and sacrificed
Looking for effects of Liqualife™ on:
• Water quality (ammonia<0.25 ppm)
• Performance of the larvae
Pompano results
Treatment
Growth Rate Standard
(mm per
Deviationday)
G.R.
Percent
survival to
12 DAH
Instant
Mortality Rate
(per day)
Liqualife Only
0.14
0.05
0.63
0.46
Zooplankton Only
--
--
0.00
0.55
Low Conc. Liqualife + Zoopl
0.25
0.08
1.04
0.51
High Conc. Liqualife + Zoopl
0.27
0.08
4.79
0.32
4 DAH
12 DAH
Conclusions
• Liqualife™ shows promise as a feed supplement for
rearing marine larvae
• Water quality does not appear to be a problem,
especially if used carefully or in a partially
recirculating culture system with a biofilter
• Challenges remain for developing protocols for use of
the product (how much, when to introduce, when to
transition to a larger size, performance for different
species)
Acknowledgements
• David Burris, Ryan Lane
• Chuck Weirich, Ken Riley