Effect Stocking Density on Growth and Survival Rate of Larval Selais
Fish (Kryptopterus lais) Cultured in Recirculation System
Agusnimar Muchtar and Rosyadi
Departement of Aquaculture, Universitas Islam Riau, Pekanbaru, Indonesia
Keywords:
Kryptopterus lais, Stocking Density, Recirculation, Survival, Growth.
Abstract:
An experiment about the effect of three stocking densities (10, 30 and 50 larvae L
-1
) on growth and survival of
the selais fish larvae, an important commercial species, and the source of income for the rural community was
conducted at the Fish Hatchery of the Agriculture Faculty, Universitas Islam Riau, Indonesia. Three-day post-
hatched larvae (0.0012±0.00 g in weight ; and 0.03±0.00 cm in length) were used as test fish that obtained
from the artificial spawning of the selais fish broods. The fish larvae reared in recirculation system with a
water flow rate of 0.05 L
-1
, and fed with silkworms (Tubifex sp).This study used a completely randomized,
non-factor design with three treatments and three replications. The best growth in weight and growth in length
(of 0.87±0.00 grams and 5.39±0.49 cm, respectively) were found in the T1 (stocking density was 10 larvae
L
-1
). The highest survival rate (57.33±7.72) was attained in T1 (stocking density was 10 larvae L
-1
) while the
lowest survival (51.60%) attained in T3 (stocking density was 50 larvae L
-1
) . Growth rate and survival rate of
the selais fish larvae were inversely proportional to the density of the fish larvae.There’s no significant effect
of stocking density on the growth and survival of the selais fish larva (P>0.05).
1 INTRODUCTION
Selais fish (Kryptopterus lais) is a kind of freshwa-
ter fish inhabits floodplain river ecosystems (Elvyra
et al., 2010), and peatland waters in the Bukit-
Batu Biosphere Reserve, (Fahmi et al., 2015), an
ecosystem that has unique characteristics in the Riau
Province. The selais fish is an important economic
commodity in Riau Province due to (1) it is very de-
licious food ingredient, liked by many peoples so that
it become important trading commodity, (2) this fish
is also a source of income for rural people because
is the main source of raw materials for the fish indus-
try, (3) these fish have the potential to be developed as
economically valuable ornamental fish (Fahmi et al.,
2015), (4) the selais are endemic fish that have the
potential to enrich fish populations in waters (stock
enhancement) and restocking to lakes and reservoirs
(Rengi et al., 2013; ?).
The population of the selais fish inhabiting fresh-
water in Riau Province decline continuously (Rengi
et al., 2013; Simanjuntak C P. H., 2008) due to
high-intensity fishing, environmental damage and the
threat of the introduction of exotic fish against native
species. The impact of the this decline in fish pop-
ulation did not only cause a decrease in fishermen’s
catches yield but also affects the stock of raw mate-
rials for the smocked fish industry and the income of
rural people.
To overcome this problem, fish farming needs to
be developed. Domestication of fish selais has been
carried out through a series of studies so that these
fish can be artificially spawned, have received artifi-
cial feed (Agusnimar and Rosyadi, 2013) and grow
optimally in cultivated with the artificial feed in float-
ing net cages (Rosyadi and Agusnimar, 2016) and in
pond (Agusnimar et al., 2015).
Stocking density is a key factor affecting the pro-
duction of cultured fish seeds, in addition to food sup-
ply and quality, genetics, and environmental condi-
tions.
An increasing in fish stocking density can in-
crease fish seed production however the increase in
fish stocking density in culture media can reduce wa-
ter quality, fish growth rate and degree of heterogene-
ity of live fish (Slembrouck, 2005) therefore, to in-
crease fish larval production by increased stocking
densities must be followed by the increasing of dis-
solved oxygen because the rate of the dissolved oxy-
gen in water can be a barrier to the survival of fish
larvae and can cause their death.
There is much larval death because there is not
254
Muchtar, A. and Rosyadi, .
Effect Stocking Density on Growth and Survival rate of Larval Selais Fish (Kryptopterus lais) Cultured in Recirculation System.
DOI: 10.5220/0009186302540257
In Proceedings of the Second International Conference on Science, Engineering and Technology (ICoSET 2019), pages 254-257
ISBN: 978-989-758-463-3
Copyright
c
 2020 by SCITEPRESS – Science and Technology Publications, Lda. All rights reserved

enough oxygen. The recirculation system can in-
crease the support of the cultivation media (Kadarini
et al., 2010).
The purpose of this study was to determine the ef-
fect of differences in stocking density on the growth
and survival of fish larvae (Kripthopterus lais) which
are maintained by a water recirculation system.
2 METHODOLOGY
The experiment was conducted at the Fish Hatchery
of the Agriculture Faculty, Universitas Islam Riau,
Indonesia, from May 10 to June 25, 2016. Three-
day post-hatched larvae (mean weight 0.0012±0.00
g; mean length and 0.03±0.00 cm) were used as test
fish that obtained from artificial spawning result of se-
lected selais fish broods in total length 90-110 cm and
average weight equal 100-120 gram.
Nine cylindrical plastic topless units were used as
experimental containers. the capacity of each topless
was 15 liters, filled with 10 liters of water A recir-
culation system connected to the physical filter and a
water pump with a water flow rate of 0.05 L
-1
was in-
stalled in this experiment. Fish larvae were stocked in
experimental media at three different density levels:
(10 larvae L
-1
, 30 larvae L
-1
, 50 larvae L
-1
) . Fish lar-
vae were fed silkworms (Tubifex sp) collected from
Sail river in Pekanbaru. The silkworms were given
to larvae using the ad libitum method. Fish growth
data were taken randomly and measured at the begin-
ning and the end of the experiment. Both weight and
length were measured (nearest 0.01 g, total length of
the closest cm, respectively). This study used a com-
pletely randomized, non-factor design with 3 treat-
ments and 3 replications as follows:
Treatment 1 (T1): rearing selais larvae with stock
density 10 larvae in 1liter water (L
-1
); Treatment 2
(T2): rearing selais larvae with stock density 30 lar-
vae in 1 liter water (L
-1
); Treatment 3 (T3): rearing
selais larvae with stock density 50 larvae in 1 liter wa-
ter (L
-1
).
The parameters observed consists of initial and fi-
nal ( weight and length) growth and survival fish lar-
vae. Base on that data the performance growth and
survival of selais fish larvae were calculated base on
the equation :
• Weight Gain (WG) = Mean final weight – Mean
initial weight
• Daily Weight Gain (DWG) = Fresh weight gain in
fish (g) / t
• Specific growth rate/day (SGR) = [(Log final
weight – Log initial weight) x 100] / t
• Survival rate (SR) = (Final number of fish/Initial
number of fish) x 100.
Performance of the growth and survival data were
analyzed by one-way analysis of variance (ANOVA)
to determine the difference in density for each treat-
ment and the least -squares difference (LSD) test was
applied when significant differences were found.
The water quality parameters such as temperature,
pH and DO was measured straight from the media
experiment in Fish Hatchery of Agriculture Faculty,
Islamic University of Riau, while ammonia was ana-
lyzed in the laboratory of the Environmental Quality
of Riau University.
3 RESULT AND DISCUSSION
3.1 Growth and Survival Rate
The weight growth of selais fish larvae effected by
different stocking density presented in table 1.
Table 1: The weight growth of selais fish larvae cultured on
diffrent stocking density.
Parameters
Weight Growth of Selais Fish Larvae
T1 T2 T3
Average Initial
weight (g)=ALW
0.0012±0.00 0.0012±0.00 0.0012±0.00
Average Final
weight (g)=AFW
0.88±0.00 66±0.00 0.64±0.00
Wight pain (g)= WG 0.87±0.00 0.66±0.00 0.64±0.14
Daily wight rate
(g) = DWG
0.04±0.00 0.03±0.00 0.03±0.01
Specific growth
rate (%/day) = SGR
13.63±0.15 13.042±0.25 12.96±0.26
As shown in table 1 that the performance of
growth weight of selais fish larvae was varied in dif-
ferent stocking densities. However base on analy-
sis of variance we found that there were no appar-
ent effects of stocking density (10, 30, 50 larvae L
-1
)
on the growth at the levels tested (P>0.05). The
best wight rate (WG, DWR, and SGR, 0.87±0.00
g/day: 0.04±0.00, and 13,63 ±0.15%, respectively)
was found in treatement of T1 (stocking density of
10 larvae L
-1
) while lowest growth rate (WG, DWR
and SGR: 0.64±0.14 g/day, 0.03±0.01, and 12,96
±0.26%, respectively ) was found at treatement of T3
(stocking density of 50 larvae L
-1
).
This result indicated that the higher stocking den-
sity the slower the weight gain, daily weight rate, and
specific growth rate/day. Prior research (Darmawan
and Suharyanto, 2017) reported the similar effects of
high stocking densities on growth of Jambal catfish
(Pangasius djambal).
The length growth of selais fish larvae effect by
diffrent stocking density presented in table 2.
Effect Stocking Density on Growth and Survival rate of Larval Selais Fish (Kryptopterus lais) Cultured in Recirculation System
255

Table 2: The Length Growth of Selais Fish Larvae Cultured
on Different Stock Density.
Parameters
Length Growth of Selais Fish Larvae
T1 T2 T3
Average Initial
Length (g)=ALW
0.03±0.00 0.03±0.00 0.03±0.00
Average Final
Length(g)=AFW
5.42±0.49 5.31±0.02 5.20±0.24
Length pain (g)= WG 5.39±0.48 5.28+0.02 5.17+0.24
Daily Length rate
(g) = DWG
0.26+0.02 0.25+0.01 0.25+0.02
Specific Length
rate (%/day) = SGR
10.74+0.00 10.70+0.00 10.55+0.00
Similar with performance of the growth weight,
the highest length growth (LG,DLR, and SLR, 5.39
±0.48 cm/day: 0.26±0.02, and 10,74 ±0.10%, re-
spectively ) of selais fish larvae was found at treate-
ment of T1 (stocking density of 10 larvae L
-1
), while
lowest length growth (LG, DLR, and SLR were
5.17±0.00 g/day : 0.25±0.02 , and 10.55±0.00%, re-
spectively) was found at treatement of T3 (stocking
density of 50 larvae L
-1
).
It was mean that the best length growth of selais
fish larvae found in the lowest stoking density. Sim-
ilar findings were recorded in other reared species
(Herrera, 2015; Huet, 1971) who achieved the best
growth of fish larvae at lower stocking densities.
The high growth (weight and length) of fish larvae
in treatment of T1 compared to T2, and T3 may be
due to fish larvae maintained with low stocking den-
sity do not spend much energy to compete using more
space and food. Haque et al. (Haque et al., 1984) said
that the fish that were kept with the lowest stocking
density provide more space, food, and less competi-
tion. So that the fish larvae in the T1 treatment (the
lowest stock density of fish larvae in this experiment)
have more energy to support the growth of fish larvae
in the treatment of T1.
Survival rate of selais fish larvae on different
stocking density was shown ini table 3.
Table 3: The Survival Rate Of Selais Fish Larvae Cultured
On Different Stock Density.
Replication
Survival rate selais fish larvae(%)
T1 T2 T3
1 68,00 50,67 54,00
2 54,00 62,67 52,00
3 50,00 52,00 48,80
Total 172,00 163,33 154,80
Average 57,33 55,11 51,60
In table 3 was shown that the survival rate of selais
fish larvae was varied (T1,T2, and T3 was 57,33%,
55,11%, and 51,60%, respectively) in different stock-
ing densities. However base on analysis of variance
we found that there were no apparent effects of stock-
ing density (10, 30, 50 larvae L
-1
) on the survival at
the levels tested (P>0.05). The best survival rate was
found in T1 (stocking density of 10 larvae L
-1
) while
lowest growth was found at T3 (stocking density of
50 larvae L
-1
).
The results of this study also show that the sur-
vival rate of selais fish larvae is inversely proportional
to stocking density. The higher stocking density, the
lower the survival of fish larvae. This means that
stocking density is a determining factor for the sur-
vival of fish larvae. According to Herrera (Herrera,
2015) stocking density affects survival, growth, be-
havior, health, water quality, food, and production.
The survival rate of fish larvae in this study was
relatively low (<58%) because of the high mortality
of larvae during the study. The high mortality rate of
fish larvae in this experiment may be caused the test
fish larvae used in this experiment were pre-larvae of
selais fish (three-day post-hatched larvae mean weight
0.0012±0.00 g; mean length and 0.03±0.00 cm).
while another research (Efendi et al., 2016) found that
the survival rate of post- larvae of selais fish larvae
feed Tubifex sp enriched with probiotic was reached
98%, The survival rate of selais fish larvae can be in-
creased by giving probiotics through natural feed such
as Tubifex sp.
3.2 Water Quality
The result of measurement on water quality parame-
ters can be seen in table 4. The average temperature
found in all treatment was the same about 26
0
C-30
0
C.
It means the water temperature for fish larvae in all
treatment was optimal. It is stated the optimal tem-
perature for fish life is 25
0
C- 32
0
C (Boyd, 1989; ?).
The degree of water acidity [pH] in media culture at
all treatment were ranged among 6,0-6,5. Even if the
pH of the water in the research was not optimal for
fish larvae, but it still supports the growth and sur-
vival of the selais fish, According to (Elvyra et al.,
2010) selais fish (K. limpok) be able to live in the wa-
ter with a little bit acidic water that ranged between
5,5-6,0. Dissolved Oxygen (DO) in this research were
5,0 – 5,2 ppm higher than the amount of the DO
(3,16–3,45ppm) in the aerated container using aera-
tor. The height of dissolved oxygen in this research
caused by the using of recirculation system while the
debit water that entered in research container 0.05 1/
second.
The concentration ammonia (NH3) in culture me-
dia ranged between 0.29-0,63 ppm. It means the
amount of ammonia in the culture media was still in
the eligibility limit on the selais fish larvae. Boyd
ICoSET 2019 - The Second International Conference on Science, Engineering and Technology
256

Table 4: The Water Quality Parameters.
Water Quality Treatments
Parameters T1 T2 T3
Temperaturs (OC) 26-30 26-30 26-30
pH 5.0-6.0 5.0 - 6.0 5.0 - 6.0
DO (ppm) 5,2 5 5
Amoniak (NH3) 0,29 0,29 0,63
(Boyd, 1989) stated that the NH3 concentration with
ranged between 0,6-2 ppm is still good for the fish
life.
The concentration of ammonia in each treatment
was treated differently. The ammonia content in treat-
ment of T1 (0,29 ppm) is the same as the ammonia in
treatment of T2, while the highest ammonia content
is in the treatment of T3 ( 0.63). It means, the higher
the stock density, the higher the ammonia content.
4 CONCLUSIONS
Base on result and discussions, there’s no effect of
stocking densities on the growth and survival of the
selais fish larvae cultured in the recirculation system.
The growth rate and the survival rate of selais fish
larvae were inversely proportional to the density of
fish larvae. The higher the stocking density the slower
growth rate (weight and length), and survival rate.
The optimal growth rate and survival rate found at
lower stocking densities (10 larvae L
−1
).
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