Suplement XXIX

Proceedings of the Zoological Society, 1960, 13, 29-38.

On the life history of Colisa lalius (Ham.). By Late H.  K.

 Mookerjee and S.  R.  Mazumder*, Department of Zoology,

 University of Calcutta, (with twenty-three text-figures)

(Ms. received August 17, 1957. Read May 5, 1960.)

* Now Superintendent of Fisheries, Government of West Bengal.

AUTHOR’S ABSTRACT

The paper deals with bionomics, nest-building habit, sexual dimorphism, jealousy between two ripe females, breeding, development, food and rearing of Colisa lalius. The duration of spawning, period of hatching and the time required for the formation of different organs have been recorded. The developing eggs have been critically observed.

INTRODUCTION

Colisa lalius (Ham.) belongs to the group of labyrinthine fish and is commonly called dwarf gourami (Innes, 1907). In Bengal, it is named differently in different localities, such as 'Lai Kholisa’ at Goulpara (Day, 1878) and 'Tabaicha’ in the district of Noakhali.

It finds favour with the aquarists and is also considered as an edible fish. It is found in plenty in East Bengal (now Eastern Pakistan) and not to that extent in West Bengal. This fish is well known for its larvaecidal habits. On account of its diverse utility, its culture deserves to be augmented.

For its successful culture, a knowledge of its life history, breeding andrearing is necessary, but only some scanty descriptions of the morphology and the breeding habits of this fish are known (Carbounier, 1876; Day, 1878;  Innes, 1907 and 1935; Jones, 1946).

MATERIAL AND METHOD

Details of laboratory and field studies undertaken by the authors on the life history of Colisa lalius (Ham.) during the year 1942-43 are given in this paper.

The collection of eggs, fry and adolescent fishes was also made under natural conditions so as to correlate the rate of growth in nature with that under laboratory conditions.

Different stages were preserved at an interval of five to thirty minutes according to the needs for study. Embryonic and early larval stages were fixed in the Smith’s fixative and finally preserved in 4% formaldehyde. The post-larval and adult stages were kept in 4% formaldehyde.

OBSERVATIONS

General Biology:

Colisa lalius belongs to the family Osphronemidae. It inhabits the fresh water ponds, ditches, paddy fields, rivers, etc. of East Pakistan and West Bengal. It is a hardy fish and possesses accessory air-breathing organs.

It is a surface as well as bottom feeder. It is seen frequently to come to the surface of water  to inhale air and it dies if prevented from doing it. It is rather timid (Innes, 1907).

The male is vertically banded  with scarlet and light blue. The dorsal and caudal fins are barred with scarlet dots. The anal fin has a dark band along its base and red outer edge.

It has been found by experiment that the fish thrives in the aquarium.

Breeding colouration:

During the breeding season  the scarlet colour and bluish tinge in the male become  intensified, while in the female the dark lateral band on the body becomes prominent. The colouration develops before spawning, but gradually loses its intensity afterwards.

Breeding season:

Mallen and Lanier as quoted by Jones (1946) say that it breeds several times during the summer at a temperature of 75°F. In Bengal this fish was observed to breed in natural conditions though much has been recorded regarding its breeding habits in aquaria.

This is a bubble-nest builder. Innes as quoted by Jones (1946) attributed to it the merit of building a bubble-nest with bits of plants. This fish was observed to build up nests of bubbles in paddy fields and in seasonal tanks, but never in stagnant perennial tanks. During breeding season after or during rains they are found to migrate to paddy fields or other seasonal waters from the stagnant perennial waters. They migrate by water courses and not by land route. Both the male and the female build nests of bubbles to which are added bits of Hydrilla, Ceratophyllum or Spirogyra sp. When the construction of the nest is complete, the female goes just below the nest and the male starts sexual sports with the female in various ways culminating in spawning. The eggs float on the surface of water and the female transfers those eggs which have got outside the boundary of the nest into it. The sexual sport is repeated a number of times till all the eggs are laid. Then the male and the female are seen to guard the eggs. The temperature and the pH of water at the time of spawning were 82°F and 7.7 respectively.

Breeding under Laboratory condition:

The spawning behaviour in the aquarium was observed to be almost similar to that under natural condition. The observation on breeding habits was also confirmed by breeding in the laboratory.

Duration of spawning:

The duration of spawning was determined by direct and indirect methods. The direct method is to note the period from the time of first extrusion of the ova and its fertilization to the time of its last extrusion and impregnation during a spawning operation. Indirect method is to measure the time from the moment of earliest hatching to that of last hatching of whole lot of eggs extruded during a particular spawning. During the experiment the spawning party being hardly disturbed, the duration of spawning was found to be from two to two and a half hours. Under disturbed condition the spawning operation stops temporarily and if repeatedly disturbed, it stops altogether.

Jealousy between two ripe females:

When a mature female was introduced in the aquarium in which a male and a female of C. lalius had been engaged in spawning activities, the process was found to be delayed. The spawning female tried to drive out the rival female to deprive the latter of the chance of mating with the male partner of the spawning party.

Description of imptegnated eggs:

The eggs are small, almost circular, non-adhesive and lighter than water. They float on the surface and remain more or less collected within the nest. They are almost invisible. On extrusion, they are invested by a single layer of capsule or zona radiata. There is a clear space called perivitelline space.

Development:

The earliest stage of egg was collected about 5 minutes after the egg-laying and fertilization. It is highly laden with yolk and more or less spherical in shape measuring on an average 0.7 mm in diameter. The early embryonic development follows the same processes as have been observed in Wallago attu (Bloch & Schneider), the only difference being the presence of a mass of oil globules at the distal end of vegetal pole enclosed by a thin layer of protoplasm (Mazumdar, 1957). A number of oil globules persist until the larva hatches out. In the 60 minutes old egg, the protoplasm has aggregated to form a cap-like structure on the yolk mass known as blastodisc, and the swelling at this stage is known as blastodisc, and the swelling at this stage is  is perhaps at its maximum, and the size of the egg as a whole is 0.79 mm (Text-fig. 1).

Cleavage:

At the seventy minute stage, the first cleavage commences. The first cleavage is indicated by a slight dipping in the middle of the blastodisc at the animal pole. Four minutes later the blastodisc is divided, but not separated from each  other (Text-fig. 2) and the two blastomeres are formed. Within two hours’ time five cleavages take place resulting in the formation of a thirty-two celled stage up to which the cleavage can be followed easily. The second division is meridional and perpendicular to the first and the third parallel to the first. The fourth division is parallel to the second (Text-figs. 3-5).

Yolk  invasion:

On further divisions the loose cells at the basal region spread out in thin layers with a very faint and indistinct margin over the yolk. Fifteen minutes later the cells form a regular blastoderm layer extending over one-eighth of the circumference of the yolk with a very faint indistinct margin and within about six hours the blastoderm invades the yolk completely leaving a space representing the position of the blastopore. During the process of yolk invasion signs of the commencement of the formation of embryonic ridge or neurocord are observed (Text-figs. 7-10).

Embryo formation  and hatching:

By the eighth hour the multilayered ridge is fully formed along the anteroposterior axis. The head of the embryo appears arrow-shaped with two lateral projections attached to the neurocord anteriorly. Behind this region the hind brain is formed and the mesoblastic somites are visible. Later, the heart is formed and the mesoblastic somites increase to twelve in number. The optic rudiments on each side arise as solid epidermal outgrowths. The heart becomes tubular and pulsation commences. Kuffer’s vesicle appears anterior to the tip of the tail. A groove appears in the region of the hind brain and the blastopore closes. The groove extends backward and forward and the brain is distinguished into fore, mid and hind regions. At first, some pigments make their appearance on the yolk and nape and with age these become dense. Some pigments aggregate on the head and the tail. The epiblastic involution for the formation of the optic cup is visible as also a thin membranous finfold which gradually broadens. The otocysts are formed of the thickened area on the hind brain. The tail becomes free from the yolk mass. The rate of heart beat now is 160 per minute and the muscle segments double in number. The notochord appears vacuolated. All the embryonic developmental processes take place within twenty one hours of fertilisation (Text-figs. 11-12). At this stage the embryo hatches out,  the hatching temperature being recorded at 85° to 86°F and the pH-value during these processes 7.7.

Newly hatched larva:

On emergence, the larva measures 1.5 mm in length (Text-fig. 13) and comes to rest on the water surface upside down. The head and trunk still remain attached to the yolk-mass. The median fin-fold extends ventrally to posterior margin of the yolk-sac. The mouth is not open. Epiblastic involutuon of the optic outgrowth deepens to form lens and the border of the otocysts becomes thickened. The tail is bent towards ventral side and symmetrical in form. The vent lies behind the yolk-sac.

Six hours old larva: The lower lip is formed. The pectoral fin-buds appear. Pigments appear on the inner border of eyes and along the ventrolateral region of the body. Lens has taken the globular form. The tail is straightened.

Eight hours old larva: The nerve ganglia and neural arches are under formation. Segmentation of vertebral column commences. The larva measures 2 mm in length (Text-fig. 14).

Twenty eight hours old larva: The eyes have gradually become horse-shoe-shaped and the pupils, black. Yolk-mass is greatly reduced. Chromatophores are arranged longitudinally on either side of the notochord. The larva measures 2.56 mm in length (Text-fig. 15).

Forty five hours old larva: The mouth opens and the larva feeds on protozoans. The anterior margin of the upper lip becomes trunketed, but it is protruded in the middle. The narial aperture lies in front of each eye. The pectoral fins elongate. The larva increases to 2.63 mm in length (Text-fig. 16).

Four days old larva: Gape of the mouth increases. The air-bladder is visible and globular.

Five days old larva: Neural and haemal spines are under formation. Yolk is fully absorbed. Heart is divided into auricle and ventricle. The larva is capable of active swimming and starts feeding. The larva increases to 2.66 mm in length (Text-fig. 17).

Seven days old post larva: The dorsal profile is convex. There are pigment dots on the snout. The body is transparent. Chromatophores are visible on the margin of the lower and upper lips. Body is greenish from above. The length of the larva is 3 mm (Text-fig. 18).

Nine days old post larva: The ventral profile is concave. Abdomen is reduced in girth and white. Stomach hangs down. The larva measures 4.45 mm. in length.

Eleven days old post larva: The tail is asymmetrical. Hypurals and kidneys are formed. Small and large pigment dots are formed on the body and the head. Colour along the dorsal is greenish while on the abdomen, yellow. The caudal fin shows the usual number of fifteen rays. The mouth is deflected above. The larva increases to 5.5 mm (Text-fig. 19).

TEXT-FIGURE 1. Lateral Egg, collected 60 min. after extrusion, 2. Egg, 1 hr. 14 min. after fertilisation, 3. Egg, about 1 hr. 24 min. after fertilisation, 4. Egg, about 1 hr. 31 min. after fertilisation, 5. Egg. about 1 hr. 46 min. after fertilisation, 6. Egg, about 2 hrs. after fertilisation, 7. Egg, about 4 hrs. after fertilisation, 8. Egg, about 4 hrs. 15 min. after fertilisation, 9. Egg, about 4 hrs. 45 min. after fertilization, 10. Egg, about 6 hrs. after fertilization, 11. Egg, about 9 hrs. 30 min. after fertilization, 12. Egg, about 12 hrs. after fertilization, 13. Larva after hatching, 14. Larva 8 hrs. after hatching, 15. Larva, 28 hrs. after hatching, 16. Larva, 48 hrs. after hatching, 17. Larva, 6 days after hatching, 18. Post larva, 7 days old, 19. Post larva, 11 days old, 20. Post larva, 14 days old,

Thirteen days old post larva: The vertebral column becomes segmented in 24 pieces excepting the urostyle. Pelvic fin buds appear. The larva has turned opaque. Blood circulation is established in the caudal region. Colour of the blood is golden. On the next day blood gets a reddish tinge. The larva attains a length of 6.4 mm (Text-fig. 20).

Fifteen days old post larva: Dorsal fin-fold is greatly absorbed and only a vestige is continuous with the caudal fin. Ventral fin fold is continuous with the caudal.  The dorsal and the anal fins show 17 and 19 rays including spines respectively. Gill area gives out red colour.

Twenty days old post larva: The opercular bones are clearly differentiated. The pelvic fin shows the usual number of one ray. The pectoral fin shows six rays. The rays including spines on the dorsal fin are 23 (15/8). The length of the larva increases to 12 mm (Text-fig. 21).

Thirty days old post larva: It measures 19 mm. Scales are in formation. Pelvic fins have elongated. There are twelve vertical bands found along the lower half of the body. The anal fin shows 30 (17/13) rays including spines.

TEXT-FIGURE. 21. Post larva, 20 days old, 22. Post larva, 30 days old, 23. Post larva, 39 days old,

Abbreviations
For Text-figures 1 to 23

A.— Anal fin; C.— Caudal fin; D.— Dorsal fin; E.— Eye; P.— Pelvic fin; H.— Head; a.b.— Air bladder; a.p.— Animal pole; b.d.— Blastoderm; bl.— Blastodisc; b.m.— Blastomere; b.p.— Blastopore; e.r.— Embryonic  ridge; K.— Kupfer’s vescicle; l.— Lens; m.— Mouth; m.f.— Median fin-fold; o.— Operculum; o.g.— Oil globule; o.l.— Otocyst; p.b.— Pectoral bud; p.s.— Pervitelline space; v.b,— Vertical band; v.m.— Vitelline membrane; v.p.— Vegetal pole; y.p.— Yolk Plug; y.s.— Yolk-sac.

Thirtynine days old post larva: It becomes 20 mm in length. Vertical bands become very prominent. There lies a black spot on the caudal peduncle. Dorsal side is greenish, abdomen and beyond is scarlet-white. Head is yellowish brown and marked with black pigments (Text-fig. 23).

Forty one days old post larva: It is 22 mm long. The scales are fully formed. All the fins show their usual number of fin rays and spines. The post larva attains the size of a young adult.

Rearing:

Rearing in the laboratory was started as soon as the eggs hatched out and several factors, such as enemies, oxygen supply, light, food etc. were taken into account. The larvae were collected with a flat moderately large petri dish and distributed  to a number of glass aquaria with the pH of water at 7.8. The enemies, such as the larvae and pupae of dragon and damsel flies were removed. The larvae needed oxygen and a requisite area of space at the surface of water. This necessity of space was experienced in rearing the larvae of A. testudineus.  (Mookerjee and Mazumdar, 1946). Necessary steps were taken to avoid congestion and pollution of water by aerating water with motor tube (Mookerjee, 1940) and with plants. Four larvae below 3 mm in length could be harmlessly accommodated in a square inch and the number could be doubled by oxygenation with motor tube. As for the fry of 3 mm to 20 mm in length, 3 to 6 square inches for each and from 20 to 40 mm, 11 sq. ft. for each were found to be sufficient. In all these cases, depth of water was 10 inches. For the young and the adult during experiment a space 41 cubic feet for each was allowed.

The aquaria with plant were found to keep the water clean and provide extra oxygen. In the case of laboratory rearing, Hydrilla verticiliala, Vallisneria spiralis and Myriophyllum sp. were found suitable.

Aquaria practically got 6 to 8 hours direct sun which proved to be of some help for the growth of some plants that ultimately aided the fish in oxygenation. Light was also found to encourage the growth of some unicellular and multicellular algae that form the food for fishes. Algae in its turn also helped the growth of some crustaceans, such as Daphnia, Cyclops etc. and the protozoa, on which the fishes are dependent. Light also prevented the growth of disease producing bacteria and fungi.

The mouth of the larvae having opened they were fed with protozoa, such as Paramoecium, Coleps, Chaenia and other cilliates and flagellates from the culture. Gradually they learnt to take unicellular and multicellular algae from the fourth or the fifth day, but preferred protozoa. The small crustaceans, such as Daphnia and Cyclops were introduced on the seventh day of hatching, but they could not be ingested before the 11th day. From the 20th day they commenced to take small mosquito larvae and gradually took to crustacean and insect diets. Then the fry were fed with different artificial food, such as gram flour, coarse flour and with natural animal food, such as D. pulex, D. longispina, Cyclops leuckarti, Ceriodaphnia rigaordi, Cypris, Rotifers, etc. and and vegetable food, such as Closterium, Oscillaloria, Cosmarium, etc. for three months during which they attained 40 mm in length. Thereafter some were planted in ponds and others were reared in the laboratory with artificial and natural food.

It was observed that regulation of food is necessary. The excess of food forms congestion and produces troubles for the fish from lack of oxygen. The artificial food in excess caused polution of water resulting in the growth of bacteria and diseases. In order to avoid such polution of water the residual foods were removed by siphon (Mookerjee, 1942) and the foods were regulated. The changing of water during larval period was done by a rubber tubing and care was taken against the escape of the larvae and any mechanical injury to them.

 Food:

Food of fry: To determine the nature of the food of fry recourse was taken  to direct method of dissecting the fry and examining their gut contents. Eighty specimens were examined from 2.8 mm to 20 mm in length. The examination showed that the fry from 2.8 mm took fresh water cilliates and flagellates.

Fry bigger than 5.5 mm began to take small crustaceans, such as Daphnia, Cyclops, etc. and unicellular algae. Fry from 12 mm stage onwards took small mosquito larvae, worms etc. Food of fry under natural condition, thus determined, comprises both plant and animal organisms such as, Scenedesmus, Ulothrix, Cosmarium, Closterium, Diatoms, Paramoecium, Chaenia, Euglena, Rotifers, Cyclops, Cypris, and Mosquito larvae and also take the vegetable diets such as Closterium, Cosmarium, Oscillatoria, Scenedesmus and Chlorella vulgaris. They were also fed with certain artificial food stuffs, such as coarse flour, powdered meat, powdered blood, gram flour, dried and powdered shrimps made into tablets with egg albumen.

Food of adult fish: The natural food for the adult was determined by the microscopical examination of the gut contents of 100 specimens. The fishes were collected from different localities, such as paddy fields, ponds and markets. The examination of the gut contents revealed the presence of certain animal diets, such as Paramoecium, Stylonichia, Colpoda, Euglena, Rotifers, Nematodes and some eggs, Daphnia, Cyclops, Cypris and Mosquito larvae and its eggs and certain aquatic vegetable diets such as Oscillatoria, Closterium, Ulothrix, Chlorella, Diatoms and some other aquatic vegetations. This fish had liking for small mosquito larvae and crustacean food but of these were preferred.

ACKNOWLEDGEMENT

The authors are indebted to the University of Calcutta for affording necessary facilities for conducting this work.

REFERENCES

CARBOUNIER, M. 1876. Nidification du poisson arc-enciel (Colisa vulgaris) Ann. Mag. Nat. Hist., 17: 172—174.

DAY, F. 1878. Fishes of India. Text Supplement, London 375.

INNES, WM. T. 1907. Gold Fish Varieties and Tropical Aquarium Fishes. 90—91.

INNES, WM. T. 1935. Exotic Aquarium Fishes, Philadelphia.

JONES, S. 1946. Breeding and Development and Development of Indian Fresh Water and Brackish Water Fishes. J. Bomb. Nat. Hist. Soc., 19: 458.

MAZUMDAR, S. R. 1957. On the spawning habits and early development of Wallogonia attu. Proc. Zool. Soc., 10: 99—105.

MOOKERJEE, H. K. 1942. Easy Method of Cleaning Aquarium or Ponds. Indian Fanning, 12: 641—642.

MOOKERJEE, H. K. 1940. A Cheap Method of Oxygenation in Fish Culture. Ind. J. Vet. Sc. and Ani. Hus., 10: 289—90.

MOOKERJEE, H. K., AND MAZUMDAR, S. R. 1946. On the Life History, Breeding and Rearing of Anabas testudineus (Bloch) J. Department of Science, Cal. Uni., 2: 101—140.