Reproductive behaviour of the skunk clownfish, Amphiprion akallopisos, under captive conditions

Haschick, Rory Dean (1998) Reproductive behaviour of the skunk clownfish, Amphiprion akallopisos, under captive conditions. Masters thesis, Rhodes University.

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Abstract

The objectives of the study were to determine whether or not behaviour could be used to predict spawning in Amphiprion akallopisos, and to document the behaviour of this species under various environmental conditions in captivity. The spawning behaviour of A. akallopisos was studied and quantified. Three behaviour patterns - belly touching, nest cleaning by the female and mutual nest cleaning (by the male and the female)were identified as predictors for spawning. The reproductive behaviour of A.akallopisos under three photoperiods was investigated. The photoperiods were: 14L:I0D, 10hrI5minL:13hr45minD and a natural photoperiod cycle condensed into three months. A. akallopisos maintained under 14 L: 10D exhibited a significantly higher frequency and duration of chasing, nest cleaning and total interaction compared to fish kept under 10hrI5minL:13hr45minD. A photoperiod of 14L:lOD was selected for further studies. As manipulation of photoperiod did not induce spawning, GnRHa was administered to the fish in the diet at levels of 10,20,40 and 80,ug!kg BW. Control groups were fed untreated food. None of the dosages were successful in inducing spawning, or spawning behaviour in A.akallopisos.It is possible that the method of hormone application was not suitable for this species. It is also possible that behaviour may regulate blood hormone levels as opposed to endocrine status influencing behaviour. In the third trial, A.akallopisos was maintained with, and without sea anemones in order to determine whether or not anemone hosts are necessary for spawning. The presence of anemones did not induce spawning and A.akallopisos kept without anemones exhibited significantly more interactive behaviour than fish kept with hosts. Spawning of A.akallopisos at a later date without anemones suggests that anemones are not necessary for spawning in A.akallopisos. Light intensity was investigated as a cue for spawning. The reproductive behaviour of A.akallopisos was then studied under light intensities of 4.16 x 1015 quanta.sec-l.cm-2, 8.85 x 1015 quanta.sec-l.cm-2 and this intensity plus natural light. Spawning occurred mainly under 8.85 x lOIS quanta.sec-l.cm-2. Fish maintained under this light intensity exhibited significantly more of nest cleaning behaviour in terms of frequency and duration than fish maintained under low light intensity. A minimum light intensity of 8.85 x 1015 quanta. secl. cm-2 is recommended for conditioning ofthis species. This study can be of practical relevance to hatchery managers who can use the methods developed and record predictors for spawning in A.akallopisos and other Amphiprion species. In this way imminence of spawning may be estimated. Most importantly, the study also has academic merit as little work has been undertaken in this field. Although the observational method used in this study was adequate for the purposes of the investigation, future work of this nature should incorporate other methods of documenting gonadal development such as gonadal staging and GSI in order to obtain more conclusive results.

Item Type:Thesis (Masters)
Uncontrolled Keywords:Behaviour, Spawning, Predict, Amphiprion akallopisos, Environmental conditions, Captivity, Male, Female, Belly touching, Nest cleaning, Predictors, Photo period, Hormone application, Blood hormone levels, Endocrine status, Sea anemones, Light intensity, Hatchery, Management, Gonadal development
Subjects:Q Science > QL Zoology > Chordates. Vertebrates > Fishes
S Agriculture > SH Aquaculture. Fisheries. Angling
Divisions:Faculty > Faculty of Science > Ichthyology & Fisheries Science
Supervisors:Hecht, Tom and Kaiser, Horst
ID Code:3023
Deposited By: Philip Clarke
Deposited On:22 Jun 2012 07:06
Last Modified:22 Jun 2012 07:06
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