Interspecific and intergeneric hybridization studies were carried out in H. longifilis, C. gariepinus and C. anguillaris under controlled hatchery conditions to estimate their aquaculture potential in terms of fertilizability, hatchability and survival. Fertilization rate in all the nine genetic crosses ranges from 60-87.5%, the fertilization rates of the parentals being significantly higher(P<0.05) with highest value of 87.5% obtained in C. gariepinus. The intergeneric hybrids had the lowest rate of fertilization. Hatchability ranges between 75- 88.1 %, with the parental C. anguillaris being slightly significantly higher than the other genetic combinations. C. anguillaris x H. longifilis I had the lowest hatchability and there was no significant difference (P<0.05) in percent hatching among the the interspecific hybrids. The survival of all the nine genetic crosses from hatching up to the end of the two weeks indoor rearing period ranges between 78-89%, which wasn't significantly different among the interspecific and intergeneric hybrids. C. anguillaris and C. gariepinus had the highest percent survival which was significantly different from all the other mating combinations. The intergeneric hybrid larval had significantly greater (P<0.05) length in comparison to the interspecific hybrids. H. longifilis and the hybrids produced from its eggs had greater body weight than that of C. gariepinus and C. anguillari

Adebayo, O.T.

Akinwande, A.A.

Fagbenro, O.A.

Aquatic Commons

11
Il'ITRODC enON
The Clariid catfishes from \\ ild and fanned sources are economically important food fish and have.
gained much prominence and species or Clarias and Heterobrauchus are widely cultured (Huisman
and Richter. 1987). Clarias gariepiuuv is closely related to Clarias anguillaris. both belong to the
same genus (Tcugels 1982. 1986). The two species are sympatric in Nigeria with very little external
difference between them (Bencch et al. 1993; Rognon ct al. 1998: and Teugcls 1998) and are only
distinguished morphologically by the number of gill rakers on the first branchial arch. In C.
gariepimts, the number is high (up 10 110) while in C. anguillaris it is Iowertless than 50). At the
genetic levcl.jhe two species are also very close with a Neis genetic distance of 0.1(, (Rognon C! (II.
1998) and P distance 0.U4 (Nwafili and Gao 2007). Genetic techniques have been applied to other
animals to improve their quality but that of fish is not yet fully exploited. Globally, efforts aimed at
genetic improvement have generated a lot of interest on the promising potentials of genetic principles
to raise aquaculture productivity (Aluko, 1999). The most current advances in aquaculture production
have been achieved through the application of genetic principles which includes selective breeding,
hybrid ization chromosome man ipulation, sex reversal and gene transfer (Aluko and Olufeagba, 1999).
The application of these genetic tools is known to have increased fish production from a mere 0.(>t tu
a maximum of 10-12 t/ha/ year in India (Roderick, 1988). Hybridization has been found to be a
breeding programme that tries to find mating combinations between different populations of fish
which produce superior offspring for grow-out, which exhibit hybrid vigour (Tavc. 1993).
Hybridization has been used to increase growth rate, manipulate sex ratios, produce sterile
animals. improve flesh quality. increase resistance, improve tolerance to environmental extremes and
improve a variety or other traits that make aquatic animals production more profitable (Dunham e:
al., 2001). Hybridization between species can also result in offspring that are sterile or have
diminished reproductive capacity. The more distantly related the two species, the greater likelihood
of their hybrid being sub-viable or sterile (Chevassus, 1983). Interspecific hybridization has been
carried out in C. batrachus x C gariepinus (Rahman et a/.1995. Sahoo et al ;2000) and C gttriepinus .r
C macrocephalus. (Yalkoob and Ali.1994) but with varying level of success. About eleven
intergcneric hybrids have been produced among members of the three genera: viz ; em/a. Labeo and
Cirrhinus involv in~ rive species of these hybrids. Those between Rohu .v Catla. Catla .r Rohu and
Catla x Mrigal. showed improved growth performance and more flesh content than the parent species
(Reddy et al., 1997). There are limited studies un experimental hybridization in C gariepinus x C
angulllaris . The hybrid cross between Heterobrauchus and Clarias species is receiving considerable
attention in Africa particularly Nigeria. These hybrids have been reported to show heterosis (Madu, et
al.. 1992, Salami et al., 1993). The study reported here with C. angulllaris, /I longifilis and C.
ABSTRACT
Interspecific and intergencric hybridization studies were carried out in H. longifilis. C gnriepinus and
C. anguiltaris under controlled hatchery conditions to estimate their aquaculture potential in tams of
fcnilizability. hatchability and survival. Fertilization rate in all the nine genetic crosses ranges from
W-87.So/c.. the fertilization rates of the parentals being significantly higher(P<O.05) with highest value
of ~7.5% obtained in C gariepinus. The intergencric hybrids had the lowest rate of fertilization.
Hatchability ranges between 75- 88.1 c;r, with the parental C anguilluris king slightly significantly
higher than the other genetic combinations. C a x f-I I had the lowest hatchability and there was no
~ignifjcant difference (P<O.05) in percent hatching among the the interspecific hybrids. The survival
of all the nine genetic crosses from hatching up 10 the end of the two weeks indoor rearing period
ranges bet \\ een 78-XlJlf:-"which wasn't significantly di fferent among til,: interspeci tic and inrcrgeneric
hybrids. C anguillaris and C gariepinus had the highest percent survi val which \\ as significantly
different from all the other matinj; combinations. The intcrgeneric hybrid larval had significantly
greater (P<O.05) length m comparison to the interspecific hybrids. II longifilis and the hybrid'
produced from its eggv had greater body weight than that of C gariepinus and C anguillaris.
A.A. Akinwande!", O.A. Fagbenro" & O.T. Adebayo"
'Federal College of Freshwater Fisheries Technology, New-Bussa,
20cpartmcnt of Fisheries and Aquaculture Technology
Federal university of Technology. Akure
FEHTILlZATION, HATCHABILITY, SURVIVAL AND LARVAL lHO\1ETRY li'\
INTERSPECIFIC ANO INTERGENER]C HYBRH)S OF CLARIW CATFISHES
12
Hybrids and control groups were produced on the same day in each experiment. One thousand (1,000)
eggs were used for fertilization for each mating combination. The number of eggs were estimated
using gravimetric method (i.c. no of eggs!g).The translucent eggs containing embryonic eyes at the
time of polar cap formation ( about 20minutes after fertilization) were considered fertilized and
counted to calculate percentage fertilization. Opaque eggs were considered unfertilized. Percentage
fertilization (%) was calculated as number of fertilized eggsl total number of eggs fertilized x 100.
Percentage hatchability was estimated using both numerical and volumetric methods. The number of
hatchlings in each mating combination were obtained by (1) direct counting of unhatchedeggs as well
as the number of hatchlings in the incubating troughs (numerical method) and (2) volumetric method
which involves random collection of fry using glass beaker of known volume in each hatching trough
011 third day of hatching using glass beaker of known volume .when the swim- up fry were already
evenly distributed. The mean number of fry was estimated used to extrapolate for the number of fry in
the calculated volume of water in each trough, for each mating combination. Percentage hatchability
(%) was calculated as; number of hatchlings! total number of eggs fertilized x 100. When more than
60% of the eggs hatched. the length of the larvae. along with the size of the yolk sac was measured to
below the nearest half mm using an ocular micrometer under a compound microscope at a
magnification of 10",. Wet weight of the larvae was recorded to an accuracy of 0.01 mg using a digital
electronic balance. Two hundred. three days old fry frOI11each genetic cross were stocked in duplicate
batches in fibre plastic tanks (60 )(40x lfkrrr') with continuous flow through system (plate 2). Pooled
weight of fry were taken. fry were fed ad-libitum with Anemia nauplia (shell free). Siphoning of
uneaten food was done every morning and evening. The daily survival was monitored and the study
lasted for 14 days.
Variations in the data generated from parameters in the various mating combination were
evaluated using Analysis of variance (ANOYA) at 95% probability level. while Duncan New multiple
Range Test (DN1'.{RT) was employed to ascertain the difference between means of parameter with
significant difference using SPSS version is.O.
Parentals (pure Line).
Clarias gariepinus (is) x Clarias gariepinus (~)
Clarias anguillaris (is) x Clarias anguillaris (~)
Heterobranchus longifilis (0) x Heterobranchus longifilis (¥)
B Interspecific hybrids
Clarias gariepinus (0) x Clarias gariepinus (~)
Clarias anguillaris d) x Clarias anguillaris (~)
C Intergeneric hybrids
Clarias gariepinus (C) x Heterobranchus longifilis (~)
Heterobranrhus longijilis (0) x Clarias gariepinus (<?)
Clarias anguillaris (is) x Heterobranchus longifilis (~)
Heterobranchus longifilis (0)x Clarias anguillaris (~)
MATERIALS AND METHODS
The project was carried out using the facilities of the Hatchery Unit of Federal College of Freshwater
Fisheries Technology. (FCFFf), New Bussa. The parental broodstocks used in this study; C.
gariepinus, C. anguillaris and H. longifilis were obtained from the concrete tanks of the Fish Genetic
Improvement laboratory of the National Institute for Freshwater Fisheries Research, New Bussa.
Gravid females were weighed individually and injected intramuscularly with ovaprim at a dosage of
0.5 mil kg of body weight (Leu and Chou. 1996). The injected breeders were kept in well aerated
holding concrete circular tanks (2.200cm3). Stripping of females was carried out after a latency period
of 12 hours for Clarias (Madu, 1989) and 15 hours for H. longifilis (Olufeagba, 1999), by gentle hand
stripping into clean bowls. In order to strip both Clarias spp and H. lougifilis at the same time; the H.
longifilis were injected 3 hours before the Clarias spp. The males were sacrified, testes is removed
into clean petri dishes and milt were collected by maceration of the testes and mixed with 0.9% saline
(Nael solution) (Woynarovich and Horvath, 1980). The eggs and milt of the parents were mixed
together to generate nine different mating combinations (genetic crosses) as follow
gariepiuus was undertaken to assess the viability and survival of their hybrid progenies during indoor
rearing operation.
13
The length of the yolk sacs did not indicate any difference in the parental H. longifilis and hybrids
of; C g x H Land C a x H 1(using maternal H longifilis) as shown in Table 2.0. Their yolk sae length
were significantly greater compared to all the other mating combinations. The average length of the
intergencric hybrid larvae were significantly greater (p<O.OS) than that of the interspecific hybrids and
the parentals. C. anguillaris larvae had the least length. H. longifilis larvae had the highest weight in
all the mating combinations. A significant greater average larval weight were observed in the
intergeneric hybrid produced from the H. longifilis eggs in comparison to the parental C. gariepinus
and C. anguillaris. The larval weight did not vary between the parental C gariepinus and the hybrids
produced from C. gariepinus eggs but were Significantly greater than C. anguillaris larvae or its
maternal hybrids.
The percentage survival of the offspring of the various mating combinations at the end of the
two weeks in indoor rearing period is shown in Table 1.0. Consider ing the three parental mating
combinations. the end of 2weeks indoor rearing, the offspring of C anguillaris had the highest
percentage survival of 89%, closely followed by those of Cgariepinus (86%) and least value of ~:m%
were recorded in the offsprings of H longifilis. The interspecific hybrids of C gariepinus (0) x C
anguillaris (~) had 80% while the reciprocal cross C aneuillaris (0") x C gariepinus (':f') produced
offspring's with 81<Ji, and were not significantly different ( P >O.()()5).The imergcncric hybrids had
tbe least survival rate with highest value of 82% in H 1(2') x C a (~) but not significantly different.
Among the intergeneric hybrids. HI (0) x C a (2) had the highest survival or 74%, followed by those
oCC a (0),. HI Cf) and HI (6') xC s (Sin with values of 72% and 70%. respectively.
a.b.c.d values WIth different superscnpts 10 each column are significantly different (P<O.OS).
Ig of C garicpinus egg was estimated to have 700 eggs;
Ig of C gariepinus egg was estimated to have 692 eggs;
19 of H longifilis egg was estimated to have 520 eggs.
Mating No. of eggs % % % survi val at
combination fertilized fertilization hatchability 2 weeks (indoor)
Parental
Cg x Cg 500 87.5C1 86.5~D 860
Cax Ca SOO 85'0 88.1 an 891)
HlXHl 500 85cd 80ab 80·
Interspecific
CgxCa 500 sc= 79.1'11 80'
CaxCg 500 77.SDc 83.31b 811
Intergeneric
JIL x Cg 500 so= 77.2a 80S
CgxHL 500 75b 78.S"1> so'
m.x c, 500 77.Stw:. 76.8" 82·
CaxHL SOO 60" 7S" 781
Table 1 Fertilization, hatchability and survival of fry in the various mating combinations.
RESULTS AND DISCUSSION
The percentage fertilization, hatchability and survival of the various offspring produced by all the
mating combinations are shown in Table 1.0. Percentage fertilization were highest in the parental
combination with C gariepinus having the highest value of 87.5% which was significantly different
(p<0.05). There were however no significant difference (p>O.05) between C anguillaris and H
longifilis. Lowest percentage fertilization were recorded in the offsprings of the intergeneric
combination with least significant value of 60% recorded in the C anguillaris Cd') x H longifilis (:;? ).
The least significant difference showed significant difference (P<O.05) in the percentage fertilization
in all the mating combinations. Hatchability ranges between 75-88.19% with the highest values
recorded in the parental combination and least in the offspring of the intergeneric combinations. There
was slight significant difference (p«)'OS) in percentage hatchability in the various mating
combination. C. snguillaris recorded the highest value of 88.19% while the least value of 75. % was
recorded in C. anguillaris Cci') x H. longifilis (g) (Table 1).
17
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Andrezey, Sand Zdzislaw. F..S. (2005). Polycyclic aromatic hydrocarbons in smoked fish - A critical
Review, Department of Food Analysis and Quality Assessment. Gdansk Uni vcrsity of
Technology, G. Narutowicza 11112. RO-952. Gdansk, Poland.
AOAC (2000). Association of Official Analytical chemist. Official Methods uf Analysis is" Edition
. Washington J).c.
Balogun, D.C. and S.!\. Surnbclla, (2001). Evaluation of flavour and colour of Clurias gartepinus
(Linnachs) smoked with different tropical Savannah hardwoods. Africa Journal oj science (//1(1
Technology I (1&2): 34-36.
Bronwell, B. (l9H.'5). A Practical Guide to Improved Fish smoking in West Africa. Washington D.C.
, United Nation children Fund. Pp.263-264.
Clifford. M.K.; Tang. S.L. and Eyo. A.A. (1980). Smoking of foods. Process Biochemistry. June/July
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Eyo,AA. (I ()R.'5). Evaluation of colour and flavour of ri~ ~ with .different wood types.
T . S' ?S'?(:- "70 . " '~~ ...roptcs CI. _ .. _ l)-~ . '''. . ..
Eyo, A.A. (1992). "1he role of Fisheries Technology ttl ulf' of l-'jSheric~ Resources. In:
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Fisheries Promotion Project Technical report Series )) tsp..
Eyo. A.A (199R). Shelf-life of moon fish (Cil/wrililfs ci ..fish !MOITIII.''rUS mille)
during storage at ambient temperature and on ice. FAO . ;,;-t
Eyo, A.A. (200t). Fish Processing technology in the Tropics Uni of Ilorin Press pp.112-129.
FAO. (1970). Smoke curing of fish. FAO Fisheries Report. No. HR.Rome: Food and Agriculture
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Wuod type SENSORY PARAMETERS I
Flavour Colour Firmness Aroma General
acceptability
Nccm 4.19 4.52 4.57 4.23 3.66b
Parkin 4.38 4.38 4.14 4.42 3.711>
Terminalia I 4.66 4.47 4.57 4.52 4.563
Table 3: Organoleptic evaluation of fish samples uc;ingvarious wood types.
The organoleptic evaluation in Table 3 showed significant difference on the general acceptability of
fish sample smoked dried uc;ing tcnninalia wood. Eyo (1985) reported significance di ffcrence in
flavour and firmness of muscle Irom smoked-dried Orechroniis niloticus using terrninalia wood. He
reported that AJu,/io africaua gave objectahlc colour and flavours to the fish. Balogun and Surnbella
(200 I) in their report indicated that wood type affect the colour and flavour of smoked dried fish
samples. The findings from this study showed that wood type has effect on the nutrient cumposition
of smoked dried fish. for the health of consumers, it may be necessary [or fish processors to takc into
consideration the wood types used in fish smoking process.
Wood type Tannin Phenolic
compounds
Neem +++ -
Parklu + ++
'j'e1'111 iual ia
-- -
Table 2: Phytochemical Analysis of wood types.
Table 2. shows the result of the phyto-chemical analysis of the various wood types used. Result
showed the presence of tannins and Phenolic compounds In Parkia. tannins in Neem tree while
terrninalia had neither of these compounds. This might possibly explain the high percentage of
protein in the experimental fish sample smoked-dried with Terminalia wood. Andrezey et al, (2005)
reported the presence of polycyclic aromatic hydrocarbons deposited from wood smoke on fish while
Rosa et al.. (2007) reponed the presence of volatile compounds in smoke dried salmon. It appear
from these tindings that tannins affect the protein content in the smoked fish sample (Tables J and 2).
FAO (1996). Smoke Curing of Fish FAO. Fish report (88) 43pp. FLLT/R88, AOIVN.
Mumbe, P.P. and Jose, M. (2005). Nutrient Composition of Selected Fresh and Processed Fish.
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Innovation and Safety, Biotechnology and New products, Skulagata 4, V L09 pp. 184-195.


Fertilization, hatchability, survival and larval biometry in interspecific and intergeneric hybrids of Clariid catfishes

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Fertilization, hatchability, survival and larval biometry in interspecific and intergeneric hybrids of Clariid catfishes

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