Embryonic and larval development of critically endangered riverine catfish Rita rita - 5-13-110-118-EJOB-11-15-RN.pdf

Muhammad Fazlul Aw al Mollah1, Khanam Taslima1* , Harunur Rashid2, Zakir Hossain1, Muhammad Nasif Sarow ar1, Muhammad Rakibul Kabir Khan3

1Fisheries Biology and Genet ics Department, Faculty of Fisheries, BangladeshAgricultural University, Mymensingh, Bangladesh2Fisheries Management Department, Faculty of Fisheries, Bangladesh AgriculturalUniversity, Mymensingh, Bangladesh3Surgery and Obstetrics Department, Faculty of Veterinary Science, BangladeshAgricultural University, Mymensingh, Bangladesh

* Corresponding Author: [email protected]

Embryonic and larval development of crit icallyendangered riverine catf ish Rita rita

©EurAsian Journal of BioSciences, 2011 110

EurAsian Journal of BioSciences Eurasia J Biosci 5, 110-118 (2011)DOI:10.5053/ejobios.2011.5.0.13

Bangladesh is a land of high potentialw ater resources w here inhabits 260f reshw ater f ish species, 24 f reshw aterpraw ns, 475 marine f ish species, 36 marineand brackish w ater shrimps and 16 exoticspecies w hich supplying around 58% ofanimal protein (Anonymous 2010). At least55 species of freshw ater catf ishes belongingto 35 genera have been recorded inBangladesh (Rahman 2005). Rita rita is one ofthem popularly know n as Rita in Bangladeshand also in India. The f ish being greenishbrow n above, brow nish w hite below w ith anextremely slimy body w hich prefers muddy toclean w ater as their habitat.

54 f ish species of inland w ater ofBangladesh are considered as either inendangered or crit ically endangered situation.Rita rita (Hamilton, 1822) is categorized as

crit ically endangered f ish (Anonymous 2000).Once the abundance of this f ish w as very richin Afghanistan, Pakistan, India, Nepal,Bangladesh and Mayanmar (Tripathi 1996).But the availability of this f ish is decreasingday by day due to the ecological changes ofthe breeding ground. As a result breedinggrounds are losing their suitability to be usedby the species posing a great threat ofextinction and t ill now it is not possible tocollect the fry of this f ish from the riversystem w here they breed naturally.

Although Rita is a tasty, commerciallyimportant, crit ically endangered catf ish ofIndian subcontinent, published reports on itsinduced breeding and rearing are quite scantyand no reports are readily available on the

Received: July 2011Accepted: October 2011Printed: November 2011

INTRODUCTION

Research Note

AbstractThe present study w as carried out to investigate the embryonic and larval development offreshw ater catf ish Rita rita. The mature eggs and sperms were collected by using artif icialinseminat ion technique and fert ilized eggs were incubated in mini circular hatchery w ithprovision of continuous water supply. The fert ilized eggs were transparent, demarsal,spherical, non-adhesive and brownish in colour w ith a diameter ranging between 1.3 to 1.6mm. First cleavage occurred w ithin 25-30 min post-fert ilizat ion at temperature of 28± 1° C.Hatching started 22 h post-fert ilization and completed w ithin 24 h at the same temperaturerange. New ly hatched larvae w ere 2.0 mm in length devoid of mouth and pigmentation andstarted feeding w ithin 48-60 h post-hatching. To date, this is the f irst t ime the early embryonicand larval development of freshwater catf ish R. rita is described. Thus the f indings of thepresent study provide valuable information that may help establishing the large scale seedproduct ion technique of Rita.Keywords: Embryo development, larva, metamorphosis, Rita rita.

Mollah MFA, Taslima K, Rashid H, Hossain Z, Sarowar MN, Khan MRK (2011) Embryonic andlarval development of crit ically endangered riverine catfish Rita rita. Eurasia J Biosci 5: 110-118.DOI: 10.5053/ejobios.2011.5.0.13

developmental biology and larvae rearingtechnique of this species. Earlier attemptshave been made to study its length-w eight(Lal and Dw evedi 1969), age and grow th(Devi et al. 1990), environmental impactassessment (Mukhopadhyay 1994),morphometric characters (Devi et al. 1991),food (Devi et al. 1992), maturity andfecundity (Saxena 1972), structure of the skin(Mital 1968) and reproductive biology of R.rita (Amin et al. 2008). Recent success ininduction of breeding of R. rita w as performedby using PG (Mollah et al. 2008).

Considering the enormous importance ofRita fish, early life history informat ion is anessential requirement for optimization of largescale seed product ion, culture andmanagement. The present w ork is the f irstever preliminary attempt and is expected toserve as a basis for further and more intensivefuture studies. An attempt w as made toconduct this study to investigate and toprovide the detailed informat ion of theembryonic and larval development of crit icallyendangered fish (R. rita).

This experimental w orks w ere carried outin the Mini Hatchery cum Breeding Complexand the laboratory of the Department ofFisheries Biology and Genet ics under theFaculty of Fisheries, Bangladesh AgriculturalUniversity (BAU) Mymensingh. The collectedmature broods of Rita rita (Hamilton, 1822)w ere induced to spaw n throughhypophysat ion previously described by Mollahet al. (2008). After that, the eggs w erefert ilized by the normal milt . For collection ofmilt , the testes from male w ere dissected outfrom its body cavity and w ere crushed byscissor. Fert ilized eggs w ere w ashed severalt imes w ith sterile dist illed w ater and f inallytransferred to and spread as homogeneouslyas possible in mini circular hatchery (50 Lcapacity) w ith cont inuous w ater supplythroughout the incubation phase. A set offert ilized eggs w ere collected very carefullyfrom the mini plastic circular hatchery w herethey w ere in constant mot ion by using a

dropper and siphoning process. After that, itw as observed under the microscope (OlympusCX41) f it ted w ith a softw are (Magnus MIPS-Microsoft Image Processing System). Eachsample w as observed four t imes to ident ifythe developmental stages (Hanif fa et al.2003).

Fert ilized eggs w ere collected up to morulastage every 15 min and then every one hourinterval until hatching and every four hours forthe next. The hatching of fert ilized eggs w ascompleted w ithin 24 h. Formalin (5%, v/v)w as used for the immobilization of the larvaeduring study periods. The diameters of theeggs w ere measured by using an eye piecemicrometer. The size of the larvae w asmeasured by placing on the petri dish placedon a 1 mm graph paper (Miah et al. 2009).The w hole experimental w orks w ere done at atemperature of 28± 1° C.

Embryonic developmentThe embryonic period starts w hen the egg

is fert ilized by a sperm and ends w hen theembryo has attained the generalized organsystems as they appear in common in all thef ish (Table 1).

Unfert ilized and fert ilized eggsThe unfert ilized eggs of R. rita w ere

opaque, demarsal, spherical and w hit ish incolour measuring 1.0 to 1.3 mm in diameter(Fig. 1a). While the fert ilized eggs w eret ransparent , demarsal, spherical, non-adhesive and brow nish colour (Fig. 1b).Immediately af ter fert ilizat ion the diameter ofthe egg increased ow ing to slight sw elling ofthe egg w hich ranged betw een 1.3 to 1.6mm. Fert ilized eggs had a reddish spot(blastodisc) and readily recognizable w ith thenaked eye (Fig. 1c).

Formation of embryoThe f irst cleavage that divided the

blastodisc into tw o blastomeres w as occurredw ithin 25 to 30 min of post-fert ilization (Fig.1d). The cleavage w as typically meroblastic.While the second and third cleavage (4 and 8cell stage) w as appeared for 60 min and 90min af ter fert ilization respect ively (Fig. 1e and

Mollah et al.

©EurAsian Journal of BioSciences, 2011111

EurAsian Journal of BioSciences

RESULTS

MATERIAL AND METHODS

1f), the 16 and 32 cell-stages w ere observedbetw een 130 min and 160 min post -fert ilizat ion, respectively (Fig. 1g and 1h).Gradually the successive cleavages w erefound, but the blastomeres w ere decreased insize. The morula stage w as completed w ithinthe durat ion of 2.75 to 3.30 h af terfert ilizat ion (Fig. 1i and 1j). During 4.0 to 4.3h of post -fert ilizat ion, the top of theblastoderm started spreading over the yolksphere formed a thin layer and the embryoreached the blastula stage (Fig. 1k and 1l).After 6.0 h of fert ilizat ion, the blastodermflat tened dow n onto the yolk-sphere. The

outer surface follow ed the curvature of theyolk sphere resulted a dome shape structure(Fig. 1m). The blastoderm began to expand(30% epiboly, about 1/4 of the yolk sphere)over the upper surface of the yolk sphereduring 7.30 h of post fert ilizat ion (Fig.1n).Within 9.30 h of post-fert ilizat ion, more thanhalf a port ion of the yolk (50% epiboly,Fig.1o) w as invaded by the embryonic shieldreached the late gastrula stage (Fig.1p). Thenaf ter 11.30 h of fert ilizat ion, the head(rudimentary brain) w as made anteriorly andthe rudimentary tail w as created posteriorly inthe dist inct embryonic body (Fig.1q). During


Mollah et al.EurAsian Journal of BioSciences

Table 1. Brief descript ions of the embryonic developmental stages of R. rita.

13.30 h post -fert ilizat ion, some of themesodermal cells divided the body of theembryo in a number of somites and alsovisibly show ed optic cups. Antero-posteriorend w as dist inguished, the cephalic port ionbecame broader and anterior end formed thehead fold, and posterior end formed the tailfold (Fig.1r). After that, 18-20 h old embryooccupied more than three fourths of the eggperipherical space and mesodermal somitesincreased in number and became more dist inctand the pigmentation w as developed in thesomites area. The tubular heart w as appearedunderneath the head and the heart act ivelystarted the blood circulat ion (Fig.1s). Beforehatching (Fig.1t), the embryo started tw istingmovement inside the egg and cont inuouslybeat the egg shell by the caudal regionespecially around the middle part of the body.This movement gradually became vigorousand the egg capsules w ere w eakened. Byrupturing the egg capsule, the middle part ofthe embryo gradually disconnected from theegg capsule. The egg membrane w as brokendow n from the caudal region and the larvafirst ly emerged w ith its tail port ion. At least 1-2 h w as required for complete emerging of thehatchling because the entire embryo did nothatch out at a time.

Larval development A larva (Latin; plural larvae) is a young

form of animal w ith indirect developmentgoing through or undergoing metamorphosis(for example, insects, amphibians orcnidarians). The larva looks completelydifferent from the adult form (Table 2).

HatchlingNew ly hatched larvae w ere straight ,

slender, t ransparent , laterally compressed

body and gradually tapering tow ards the tail.

The larvae w ere brow nish-colour and 2.0 mm

in length. The hatchlings had unpigmented

eyes and devoid of dist inct mouth and f ins.

The head w as very small and the yolk sac w as

init ially oval-shape w ith pale-brow nish colour,

w hile numerous small chromatophores at the

dorsal region gave it a dark appearance. The

larvae could not sw im and f loated passively

on the w ater and irregularly appeared upside

dow n movement . The numbers of body

somites ranged betw een 40 and 46. The

w hole hatching experimental w orks w ere

done at temperature of 28± 1° C (Fig. 2a).

8 h old larvaAverage length of the larvae w as found

about 2.1 mm and brow nish in colour. Mouthw as not yet developed but only a conspicuousdepression identified the posit ion of mouth. Adepression at the posterior end of the yolk sacw as visible w hich w as ident if ied as anal pore.Heart became more dist inct . Circulat ion ofbody f luid w as continued and barbels had notyet developed (Fig. 2b).

16 h old larvaSixteen hours after hatching, the larvae

w ere found of 2.2 mm in length. At thisstage, yolk sac w as part ially reduced andgradually became elongated. Heart and brainw ere clearly distinct. A tube like structurew ithin the body w as represented thealimentary canal (Fig. 2c).

24 h old larvaOne day old larva w ith reduced yolk sac

w as approximately 2.5 mm length. Eye spotw ith a dark pigmented area w as appeared onthe anterior part of the head. Barbels w erefound in the forms of t iny knobs. Pectoral f inbuds w ere seen. Mouth w as not opened andthe anal opening w as st ill closed.Pigmentation w as gradually extended all overthe body and the blood circulat ion systemw as fully developed (Fig. 2d).

36 h old larvaThe average length of 36 h old larva w as

2.8 mm in length. Dark pigmented eyes w ithspherical shape w ere visible. Distinct heartw as visible and funct ioned act ively. Reddishblood w as seen around the heart region. Fullyformed upper and low er jaw s w ere visible andgills w ere covered by the operculum. Mouthw as formed as an opening and the anal porew as also opened and caudal f in bud w asformed. Vigorous movements of the larvaew ere seen (Fig. 2e).

48 h old larvaTw o days old larva w as 3.0 mm in length

and part ial yolk sac w as presented. Dorsalregion became dark due to the format ion ofnumerous chromatophores and the





Fig. 1. Embryonic developmental stages of R. rita. (a) unfertilized egg, (b) fert ilized egg, (c) blastodisc and(d) 2 cell stage, (e) 4 cell stage, (f ) 8 cell stage, (g) 16 cell stage (h) 32 cell stage (i) early morulastage and (j) late morula stage, (k) early blastula stage, (l) late blastula stage, (m) pre- early gastrulastage (n) 30% epiboly (o) mid gastrula stage and (p) late gastrula stage, (q) head and tail budformation, (r) somite stage, (s) 18-20 h old embryo and (t) just before hatching.

(EM- Egg membrane, VM- Vitelline membrane, PS- Perivitelline space, Y- Yolk, BD- Blastoderm, BM- Blastomere, AP-Animal pole, EVL- Enveloping layer, VP- Vegetal pole, YSL- Yolk syncyt ial layer, DBL- Dorsal blastoporal lip, VBL- Ventralblastoporal lip, H- Head port ion, T- Tail portion, YS- Yolk sac)



t ransparent vent ral region w as visible.Pectoral f in folds became dist inct and therudimentary rays developed in the caudal f in.Barbels became elongated and mouth w asw ell formed. The alimentary tract becameshort, straight and dist inct and a small pouchlike stomach w as formed. Blood circulationw as w ell observed in the head, heart and tailregion. At the end of this stage, yolk sac w asabsorbed to half size and the larvae w erefound smoothly sw imming and feedingexogenously (Fig. 2f).

R. rita is a crit ically endangered f ishspecies and their culture technique incontrolled environment is not pract iced. Toprotect this species and develop their culturaltechnique, it is essent ial to assembleinformat ion about embryonic and larvaldevelopment of this crit ically endangered f ish.But there are no reports about the embryonicand larval development of this species.Therefore, the aim of the present studypotent ially invest igated and provided detailedinformation about the embryonic and larvaldevelopment of R. rita species.

The eggs of R. rita reached rapidly in theirembryonic and larval stages. The fert ilizedeggs of Rita are non-adhesive butadhesiveness of eggs is the special characterfound in other catf ishes such as Clariesgariepinus (Khan and Mollah 1998, Osman etal. 2008), C. bat rachus (Bruton 1979),

Mystus montanus (Arockiaraj et al. 2003) andPangasius sutchi (Islam 2005). The diameterof the fert ilized eggs ranged betw een 1.0 and1.3 mm. In similar study, some researchersshow ed dif ferent egg size of C. gariepinus(Osman et al. 2008). These differences mightbe attributed to the species variation andbrood size (Puvanesw ari et al. 2009). Firstcleavage of eggs of Rita w as observed w ithin25-30 min post-fert ilization at the w atertemperature of 27-28° C, but a discrepancy oft ime w as observed in case of C. gariepinus,Mystus cavasius w hich w as w ithin 40-50 minpost -fert ilizat ion reported f rom Khan andMollah (1998) and Rahman et al. (2004) at28.5 and 26° C respect ively. This variationmight be due to species difference and otherenvironmental factors. Just 1-2 h beforehatching, the embryo of R. rita show edtw ist ing movements inside the egg capsulew hich w as also found in other f ishes reportedby Puvanesw ari et al. (2009), Khan andMollah (1998) and Osman et al. (2008). In thepresent study, hatching began after 22 hpost-fert ilizat ion and completed w ithin 24 h at27-29° C w hich is similar to other f indingsreported from Puvanesw ari et al. (2009).Another report from Mollah and Tan (1982)show ed that in Clarias macrocephalus, incu-bation period w as 22 h at 30° C and 34 h at25° C but no hatching w as observed at 20° C.Time requirement of egg hatching w as inver-sely related to their incubation temperature(Rana 1990). Length of the new ly hatchedlarvae of this species w as around 2.0 mm

Table 2. Summary of the larval developmental stages of R. rita.

DISCUSSION



w hich is in the ranges of the f indings of Khanand Mollah (1998). In the present study,larvae w ere started to feed at 48 h post-hatching w hich is similar to other previouslyreported studies stated by Puvanesw ari et al.(2009).

R. rita w as selected for this study becauseit is already declared as crit ically endangeredfish, so an attempt should be taken to protectthis species from being extinct . Unfortunatelythere is no remarkable information on the

embryonic and larval development of this f ish,but this unique research w ork w ill act as baseline for further study.

The author takes the privilege toacknow ledge BARC (Bangladesh AgriculturalResearch Council) authorit ies for providingfinancial assistance to conduct this researchw ork.

Fig. 2. Larval developmental stages of R. rita. (a) new ly hatched larva, (b) 8 h old larva, (c) 16 h old larvaand (d) 24 h old larva, (e) 36 h old larva and (f) 48 h old larva.

(M- Myomere, PFB- Pectoral f in bud, E- Eye, YS- Yolk sac, UJ- Upper jaw , LJ- Low er jaw , CFB- Caudal f in bud, B- Barbel,MO- Mouth opening, V- Vertebra)

ACKNOWLEDGEMENTS

Amin MR, Mollah MFA, Nasrin S, Sayeed, MA (2008). Some aspects of the reproduct ive biology

of Rita rita (Hamilton). Journal of Bangladesh Agricultural University 6(1): 159-163.

REFERENCES



Anonymous (2000) International Union for Conservat ion of Nature, Bangladesh. Bangladesher

Bipanno Prani, IUCN Bangladesh, The World Conservat ion Union, Dakka.

Anonymous (2010) Department of Fisheries, Bangladesh, Ministry of Fisheries and Livestock,

Dakka.

Arockiaraj AJ, Hanif fa MA, Seetharaman S, Singh SP (2003) Early development of a threatened

freshw ater catf ish (Mystus montanus). Acta Zoologica Taiw anica 14(1): 23-32.

Bruton MN (1979) The breeding and early development of Clarias gariepinus (Pisces: Clariidae)

in lake Sibaya South Africa, w ith a review of breeding in species of the subgenus Clarias

(Clarias). Trans Zoological Society of London 35: 1-45.

Devi NT, Khumar F, Siddiqui MS (1991) Observat ions on the morphometric characters of the

catf ish Rita rita (Ham.) of the river Yamuna. Journal of Inland Fisheries Society of India 23(1):

52-58.

Devi NT, Siddiqui MS, Anw ar S (1990) The age and grow th of catf ish Rita rita (Ham.) from the

river Yamuna in north India. Journal of Indian Fisheries Association 20: 37-41.

Devi NT, Anw ar S, Siddiqui MS (1992) On the food of the catf ish Rita rita (Ham.) f rom the river

Yamuna in north India. Journal of Inland Fisheries Society of India 24(1): 34-39.

Hanifa MA, Nagarajan M, Marimuthu K, Jesu Arockiaraj A (2003) Embryonic and larval

development of spotted murrel, Channa punctatus (Bloch). Indian Journal of Fisheries 50:

355-362.

Islam A (2005) Embryonic and larval development of Thai pangas (Pangasius sutchi).

Development, Grow th and Dif ferentiat ion 47: 1-6.

Khan MMR, Mollah MFA (1998) Embryonic and larval development of African catf ish, Clarias

gariepinus (Burchell). Bangladesh Journal of Fisheries 21(1): 91-97.

Lal MS, Dw evedi AS (1969). Studies on the Fishery and Biology of a freshw ater Teleost, Rita

rita. 1. Racial studies. Indian Journal of Zoology 9(2): 79-90.

Miah MI, Harun MS, Rahman MM, Haque MR, Hossain MA (2009) Study on the embryonic and

larval development of an endangered species of bata (Labeo bata). Internat ional Journal of

Sustainable Crop Production 4(1): 72-82.

Mital AK 1968). Studies on the structure of the skin of Rita rita (Ham.) (Bagridae, Pisces) in

relation to its age and regional variat ions. Indian Journal of Zoology 9(2): 61-75.

Mollah MFA, Amin MR, Sarow ar MN, Muhammadullah (2008) Induceed breeding of the riverine

catf ish Rita rita. Journal of Bangladesh Agricultural University 6(2): 361-366.

Mollah MFA, Tan ESP (1982) Effects of incubation temperature on the hatching of catf ish

(Clarias macrocephalus) eggs w ith an illustrat ion on the larval stages. Malayan Nature

Journal 36: 123-131.

Mukhopadhyay MK, Vass KK, Mitra K, Bagchi MM, Bisw as DK (1994). Environmental impact

assessment on the test f ish Rita rita in the river Ganga in w est Bengal. Journal of Inland

Fisheries Society 26(1): 116-120.

Osman AGM, Wiertz S, Mekkaw y IA,Verreth J, Kirschbaum F (2008) Early development of the

African catf ish Clarias gariepinus focusing on the ontogeny of selected organs. Journal of

Applied Ichthyology 24: 187-195.

Puvanesw ari S, Marimuthu K, Karuppasamy R, Hanif fa MA (2009) Early embryonic and larval

development of Indian catf ish, Heteropneustes fossilis. EurAsian Journal of BioSciences 3:

84-96.



Rahman AKA (2005) Freshw ater f ishes of Bangladesh. Zoological Society of Bangladesh,

Dhaka.

Rahman MR, Rahman MA, Khan MN, Hussain MG (2004) Observation on the embryonic and

larval development of Silurid catf ish, Gulsha (Mystus cavasius). Pakistan Journal of Biological

Science 7(6): 1070-1075.

Rana KJ (1990) Inf luence of incubat ion temperature on Oriochromis niloticus (L.) eggs and fry.

Gross embryology, temperature tolerance and rates of embryonic development. Aquaculture

87: 165-181.

Saxena RK (1972). Studies on the maturity and fecundity of Rita rita (Ham.) of Ganga river

system. Journal of Inland Fisheries Society of India 4: 169-182.

Tripathi SD (1996) Present status of breeding and culture of catf ishes in South Asia.

Aquaculture Living Resources 9: 219-228.

Krit ik Olarak Tehlike Alt inda Olan Dere Kedi Baligi Rita rita' nin Embriyonik ve Larval Gelisimi

ÖzetBu çalisma, tatli su kedi baligi Rita rita' nin embriyonik ve larval gelisimini incelemek amaciylagerçeklest irildi. Olgun yumurta ve spermler yapay döllenme teknigi kullanilarak toplandi vedöllenmis yumurtalar sürekli su kaynagina sahip mini dairesel kuluçkahanede inkübe edildi.Döllenmis yumurtalar; seffaf , demarsal, dairesel, yapiskan olmayan, renkleri kahverengimsi idi veçaplari 1.3-1.6 mm arasinda degismekteydi. Ilk bölünme, döllenmeyi takibeden 25-30 dak.içerisinde 28± 1° C' de gerçeklesti. Yumurtadan çikma islemi, ayni sicakliklarda, döllenmeden 22 ssonra basladi ve 24 s içerisinde tamamlandi. Yumurtadan yeni çikan larvalar, 2.0 mmuzunlugunda, agizdan ve pigmentten yoksundu ve beslenme, yumurtadan çikistan 48-60 s sonrabasladi. Tatli su kedi baligi R. rita' nin erken dönem embriyonik ve larval gelisimi ilk keztanimlanmaktadir. Bu yüzden bu çalismanin bulgulari, büyük ölçekli Rita yavru balik üret imigerçeklest irilmesi için kiymetli bilgiler saglamaktadir.

Anahtar Kelimeler: Embriyo gelisimi, larva, metamorfoz, Rita rita.

Documents

Embryonic and larval development of critically endangered riverine catfish Rita rita - 5-13-110-118-EJOB-11-15-RN.pdf