Courtship and mating behaviour of a Maltese population of Aphanius fasciatus kept in laboratory culture is described. Moles showed a brightening of their coloration. increased aggression towards other moles. and paid more attention to females during the period April-October. Moles took the lead in courtship. Courtship behaviour consisted of a number of acts. Some involved touching the female and these appeared to be designed to arouse sexual interest; others served to exhibit the male's body and to inhibit the female from swimming away. Mating commenced with the female pushing itself into floating algal mots: the male responded by wrapping its body tightly round that of the female. following which ejaculation of eggs and sperm occurred.peer-reviewe

Grech, Michael

Schembri, Patrick J.

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The Central Mediterranean Naturalist, Vol 2 (2) - 1993 OBSERVATIONS ON COURTSHIP AND MATING BEHAVIOUR IN MALTESE POPULATIONS OF THE KILLIFISH APHANIUS FASCIATUS (PISCES: CYPRINODONTIDAE) Michael Grech and Patrick J. Schembri1 Department of Biology. University of Malta. Msido. Malta. ABSTRACT Courtship and mating behaviour of a Maltese population of Aph(Jnivs f(Jsci(Jflls kept in laboratory culture is described. Moles showed a brightening of their coloration. increased aggression towards other moles. and paid more attention to females during the period April-October. Moles took the lead in courtship. Courtship behaviour consisted of a number of acts. Some involved touching the female and these appeared to be designed to arouse sexual interest; others served to exhibit the male's body and to inhibit the female from swimming away. Mating commenced with the female pushing itself into floating algal mots: the male responded by wrapping its body tightly round that of the female. following which ejaCUlation of eggs and sperm occurred. INTRODUCTION The killifish Aph(Jnills f(Jsci(Jfvs Nardo. 1827 occurs in coastal marine and brackish water habitats all round the Mediterranean except in the westernmost part (Tortonese. 1986). This species is very variable and numerous races and varieties have been described, most of which are of uncertain taxonomic status (Spillmann. 1961; Tortonese 19700, b; 1973). Aph(Jnivs f(Jsc/(Jfvs is the only species of trUly brackish water fish occurring in the Maltese Islands (Despott. 1919; Lanfronco. 1958). Maltese populations apparently show some differences from other Mediterranean populations and are sometimes regarded as a distinct race (Dormanin. 1979). Moreover, different sites in the Maltese Islands appear to support different ecotypes (Zammit & Van Es, 1980). Most Maltese populations ore now declining and this species is listed as "vulnerable" in the Red Doto Book for the Maltese Islands (Lanfranco & Schembri, 1989). While there is a rich literature on the taxonomy, morphology and ecology of this species (for example: Steinitz. 1951; Cavicchioli. 1962; Torchio. 1967; Tigano. 1982; Penaz & Zaki. 1985). its behaviour has received much less attention. r or local populations. some behavioural information has been given by Zommit (1975) and by Cilia (1986) but this is' far from complete. The present work describes the courtship and mating behaviour in a Maltese population of Aph(Jnivs fosciof(Js kept in laborotory culture. 1 to whom all correspondence should be addressed. 28 MATERIAL AND METHODS Fish were collected using a hand net from the brackish water pool at the Ghadira Nature Reserve, northern Malto, where there is a thriving populotion, transported to the laboratory and housed in glass aquaria of dimensions 75 x 45 x 45cm kept outside out of direct sunlight. The water was aerated and salinity was allowed to vary between 24 ppt (winter) and 30 ppt (summer), while the water temperature was allowed to vary with the air temperature, to mimic the natural variations in salinity and water temperature in the fish's natural habitat (Hili et 01., 1990). The aquaria were provided with a tem layer of sand and with floating mots of green filamentous algae; sand and algae were obtained from the Ghodira pool. The fish were fed doily on commercial fish food (Tetro Fin and Sera-Roffy P) supplemented by live mosquito larvae. Maltese Aph(Jnius f(Jsci(J/us ore reported to breed between May and August (Zammit, 1975; Cilia. 1986). During this period, a close watch was kept on the culture tonk for fish showing signs of sexual activity. Such fish were used for observations on courtship behaviour. For these observations, individual mole fish were isolated in observation tanks identical to the communal culture tanks except that they were smaller (45 x 18 x 2Ocm) and the water was not aerated. After a settling period of 24 hours. a gravid female fish was introduced into the tonk and observations mode from behind a screen. Observations were made on ten pairs of fish during the period April - October 1988. Times were measured using a stopwatch. During the experimental period, water temperature varied between 27-310C while salinity wos 0 constant 33ppt. RESULTS In the communal culture tonks, sexually active moles were recognised by a brightening of their colorotion, their aggression towards other males, and their attention to females. Bosed on obserV()tions of courting pairs kept in observotion tonks. courtship behoviour was found to consist of a number of octs which are described below and illustrated in rig. 1. Wokhing The male hovers motionless wotching the female from a distance of between 5 -15cm. Often the mole's body is arched laterally, the caudol fin Quivering vigorously. Pursuing The mole swims after the female ata speed just sufficient to maintain a position some 3cm behind. Looping The mole circles round the female in a horizontal plane at a distance of some 15cm. The female either remains stationary or moves forword slowly. Zigzagging The mole swims ahead of the female performing alternate sharp turns tt;> the left and right. Nudging The male prods the female on the dorsol port of her head with his snout Occasionally the mole nudges the female's head ventrally. Nudging behaviour is 29 A E B F ----.... - --/' ....... , / "-I Q \ ( ~ \ ~ ~ c G Cf' o H Fig. 1 Acts in the courtship behaviour of the killifish Aphonius fosciotus drown from life. A. 8. E. Fond G show the fish in lateral view; Figs C. D and H show the fish in dorsal view. followed by the pair swimming together with the male positioned just above the female and touching her on her head. Butting Pushing mot. The male prods the female's belly with his snout. The female makes sudden attempts to push itself inside (} flooting algol Clasping This is the spawning posture and usuolly occurs ofter the female hos pushed itself inside on algol mat. The mole assumes an S-shape and wraps its body tightly round thot of the femole. Both fish Quiver the posterior port of their body. During clasping the fish may assume a horizontal, vertical or oblique orientation and may even lie upside down with their ventral aspect facing the surface. 30 Jerking Clasping usually ends in a series of rapid jerks by the female. r allowing jerking, pair contact is often broken. Courtship sequences were analysed by considering eoch of the nine oets defined above in turn and counting the number of times each of the other eight acts followed. Conditional probabilities for each two-act transition were calculated as described by Sioter (1973). These data are presented in the form of on ethogram in Fig. 2. On the basis of these data the typical coudship mating sequence seems to be as follows: Following introduction of a gravid female into the observation tank, the mole's initial reaction was 'watching' for a period of approximately 35 seconds, normally followed by furious 'pursuing' all over the available space. After approximately 2 minutes of this behaviour, the male started to 'nudge' the female. Females usually responded to this by attempting to move away from the mole. whereupon the mole showed 'looping' and 'zigzogging' disploys. ihis whole sequence of 'nudging','looping' and 'zigzagging' lasted for periods of up to 14 minutes. The sequence either terminated abruptly with the mole resuming 'watching' behaviour, or else the femole started 'pushing' into on olgol mlJt. The mole most frequently responded to this by approaching her and either 'butting' or 'closping'. 'Clasping' behoviour often occurred three or four times in succession with the female moving further into the algal mat each time. The sequence either terminated by 'jerking', if spawning wos successful. or else reverted back to 'butting' ond 'nudging'. DISCUSSION In Aphonius {osciot(Js. the mole plays the leading role and is more persistent, frequently spending long periods of time pursuing the female. Obviously this costs the mole considerable expenditure of energy, and courting moles appeor to lose weight rapidly. as indicated by their receding abdomen. The different octs making up the courtship sequence seem to hove different functions. Thus 'nudging' and 'butting', both of which involve touching the female's body, appear to serve in arousing mating interest on the pod of the female. 'Nudging' behoviour is common in the courtship displays of severo I killifish species, for example, Aphysemion occidentolis, Nothobronchi(Js rochoVl' and Riw/vs moqdolenoe (Axelrod, 1987). 'Looping' ond 'zigzogging' oppeor to serve 0 dual role. When the femole is stationory, they serve to exhibit the mole's body. However. if performed when the female is trying to swim oway from the mole. they moy be strotegies to inhibit the females from escoping; by moving slowly in front of the femole in 'zigzagging', or by encircling her in 'looping', the mole ottempts to stop the female fleeing. The role of 'clasping' appears to be that of ensuring maximum spawning success. By wrapping and pressing his body round the female's. the mole may aid ejaCUlation of the eggs since in some fish, pressure on the ovary seems to facilitote expulsion of the ova from the ovarian lumen (foster et aL, 1969). Additionally such close proximity of the partners is likely to ensure fertilization of the mojority of eggs. However. 'dosping' does not always lead to spawning. Careful examination of the algol filaments following 'closping' .31 ~r-------------------------------------~ 816 321 JERJlII'IG Fig. 2 Ethogram of courtship behaviour in the killifish Aphanius fasch/us. Arrow thickness is proportional to the conditional probability for the transition; conditional probabilities are also given as small figures; large figures are number of times the transition was observed. behaviour by a pair of fish did not always reveal laid eggs. Thus, while courtship is always initiated by the male. it is likely that spawning success is affected moinly by femole receptivity. F emotes often show resistance to courting males by fleeing from the site, or else, they moy be induced \{) participate in the mating preliminaries. but then refuse to spawn. As in mony other animal species, courtship behaviour in Aphomus fascia/us serves 32 to synchronize the adivities of both partners, ensuring release of ovo and sperm within a short interval of time, as well os providing on opportunity for mote choice, thereby reducing wastage of gametes (Halliday, 1983; wootton, 1984). ACKNOWLEDGEMENTS We are grateful to Charles Gaud, officer in charge of the Ghadira Narure Reserve, for supplying fish; to Mark Borg and Carmel Hili for information about the ecology of the Ghadiro pool; to Joseph Cilia for his suggestions regarding culturing; and to Sandro Lonfronco for drawing Fig. 2. REFERENCES AXELROD. H.R. (1987) ('omm(Jnify Aq(J(Jri(Jms. USA: TFH Publications. CAVICCHIOU, G. (1962) Considerazioni bio-ecologiche sopra Aph(Jmi;s f(Jsci(Jt(Js Valenciennes (Cyprinodontidae). Boll Zool 29: 713-719. CILIA, J.L. (1986) Aph(Jni(Js fasciat(Js . Potamon • Malta No 15: 131-136. DARMANIN, L. ( 1979) The only killifish in Maltese waters. The Sund(JY Times, Malta, March 11, p 12. DESPOTl, G. (1919) The ichthyoloqy of Ualt(J. Molta: Critien's Press; 59pp. FOSlER, R., CAIRNS, .J. &: KA[SLER, R. (1969) The flagfish Jord(Jnella f/orid(Je as a laboratory animol for behovioural bioassay studies. Proc. Acad. Nat. SO: Philadelphi(J 121: 129-152. HAlLIDAY, 1.R. (1983) Study of mote choice. In: Bateson, P. (Ed.] !J(Jte Choice. pp3-32; Cambridge: Cambridge University Press. HILI, C., AXIAK, V. &: SCHEMBRI, P.J. (1990) The Ghadiro reserve: physico-chemical characteristics of the pool. Centro, Malta 1 (5): 5-11. LANfRANCO, G.G. (1958) A complete quide to the fishes of Jhlta. Malto; Deportment of Information and Tourist Services; 74pp + plates 1-41. LANfRANCO, G. & SCHEUBRt, P.J. (1989) Vedebrates other than birds. In: Schembri, P.J. ' & Sultana J. [Eds.] Red d(Jt(J bOOk for the J,lqltese Islands. pp 129-137; Valletta, Molto: Deportment of Informotion. 33 PENAl, M. & ZAKI, M.\. (1985) Cyprinodont fishes of Lake Moriut, Egypt. folio 100/ogico 34: 373-384. SLATER, P.J.B. (1973) Describing sequences of behaviour. In: Bateson, P.P.G. & Klopfer, P.H. Perspectives in ethology. Vol. 1, pp 131-153; London: Plenum Press. SPILLMANN, C.J. (1961) Poissons d'eou douce (Faune de France 65J Paris: Libraire de 10 F oculte des Sciences. SlElNITZ, H. On the distribution and evolution of the cyprinodont fishes of the Mediterraneon region ond the Near Eost. Bonn Zooloqische Beltfage 2: 113-124. lIGANO, C. (1982) Le popolozioni di Aphanius fasclatus (Nardo 1827) della Sicilia orientale (Pisces, Cyprinodontidae). Animalta 9: 153-183. lORCHIO. M. (1967) Osservozioni e considerozioni sullo presenzo in ocque mediterronee costiere di Ciprinidi, Ciprinodontidi e Gasterosteidi. Notura : Rivista di Scienze Notufa/i 58: 235-243. lQR10NESE, E. (19700) Aphanius fasclatus Nardo, 1827: nome volido per il Ciprinodontide delle coste itolione. Ann. Mus. Civico Stor. Not . . Giacomo Dof/a '4 (suppl.): 1-3. lORTONESE. E. (1970b) Osteichtyes (Pesci osset') . Porte primo. [Founa d'itolio lOJ Bologna: Colderini. TORlONESE. E. (1973) Cyprinodontidoe. In: Hureou, J.C. & Monod, T. [Eds.] Check-list of the fishes of the north eastern Atlantic and of the Uediterranean (CLOfNAM) . Vol. 1; pp 270-271; Paris: UNESCO. . lOR10NESE, E. (1986) Cyprinodontidoe. In: Whiteheod. P.J.P., Bouchot, M.L.. Hureou, J.C .• Nielsen J. &. Tortonese. E. [Eds.J fishes of the north eastern Atlantic and the Mediterranean Vol. 2; pp 623-626; Paris: UNESCO. WOOTTON, R.J. (1984) A functional biology of sticklebacks. London: Croom Helm. ZAMMIT, C. (1975) Aphanius f(Jsciatus: a killie among non-killie keepers. limo C(Jr, Molto 13: 16-18. ZAMun, C. & VAN [S. H. (1980) Aphanius fasciatus Volencienne 1821. Killi News: J Brit. Killifish Ass 179: 141-144. Received 28th November 1991 34 

Observations on courtship and mating behaviour in Maltese populations of the killifish Apnonius fasciatus (Pisces : Cyprinodontidae)

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Observations on courtship and mating behaviour in Maltese populations of the killifish Apnonius fasciatus (Pisces : Cyprinodontidae)

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