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Honey gouramis (Trichogaster chuna) received chemical alarm cues derived from conspecific epidermal tissue and, simultaneously, the vocalization produced by a heterospecific gourami species, the sparkling pygmy gourami (Trichopsis pumila). Control trials paired water with the vocalization. In trials that received alarm cues, honey gouramis significantly increased activity relative to control trials that received water, suggesting an attempt to flee and search for refuge. When the recording of the vocalization was later replayed to test fish without any additional chemical cue, fish that had previously experienced alarm cue froze while those that had received water with the vocalization did not change their behaviour. These data indicate that honey gouramis recognize and respond to chemical alarm cues, making this report the second anabantoid species to be recorded with this response. Second, these data indicate that honey gouramis can associate risk of predation with a novel auditory stimulus, including vocalizations from other species. These data suggest the potential for vocalizations to evolve into alarm signals in this group of fishes. This article is protected by copyright. All rights reserved.

Ten novel microsatellite markers were developed and characterized from Siamese fighting fish (Betta splendens). Nine of ten markers were polymorphic, exhibiting an allelic number (NA) from 2 to 6 alleles per locus. The effective number of alleles (NE) ranged from 1.60 to 3.08 (average of 2.30). The observed (HO) and expected (HE) heterozygosities ranged from 0.13 to 0.67 (average of 0.39) and 0.29 to 0.63 (average of 0.50), respectively. Linkage disequilibrium was not significantly detected for any pair of loci, and only two loci (BettaMS23 and BettaMS28) showed significant deviations from Hardy-Weinberg expectations. Of these, six loci could be amplified in genomic DNA of the closely related species B. imbellis and three loci in B. smaragdina. These microsatellite markers could be used as a tool to investigate genetic diversity and population structure, as well as breeding programs in hatcheries.

Air-breathing fish of the Anabantoidei group meet their metabolic requirements for oxygen through both aerial and aquatic gas exchange. Siamese fighting fish Betta splendens are anabantoids that frequently engage in aggressive male-male interactions which cause significant increases in metabolic rate and oxygen requirements. These interactions involve opercular flaring behaviour that is thought to limit aquatic oxygen uptake, and combines with the increase in metabolic rate to cause an increase in air-breathing behaviour. Air-breathing events interrupt display behaviour and increase risk of predation, raising the question of how Siamese fighting fish manage their oxygen requirements during agonistic encounters. Using open-flow respirometry, we measured rate of oxygen consumption in displaying fish to determine if males increase oxygen uptake per breath to minimise visits to the surface, or increase their reliance on aquatic oxygen uptake. We found that the increased oxygen requirements of Siamese fighting fish during display behaviour were met by increased oxygen uptake from the air with no significant changes in aquatic oxygen uptake. The increased aerial oxygen uptake was achieved almost entirely by an increase in air-breathing frequency. We conclude that limitations imposed by the reduced gill surface area of air-breathing fish restrict the ability of Siamese fighting fish to increase aquatic uptake, and limitations of the air-breathing organ of anabantoids largely restrict their capacity to increase oxygen uptake per breath. The resulting need to increase surfacing frequency during metabolically demanding agonistic encounters has presumably contributed to the evolution of the stereotyped surfacing behaviour seen during male-male interactions, during which one of the fish will lead the other to the surface, and each will take a breath of air.

One new and three previously described species of Trianchoratus Price et Berry, 1966 were collected from the gills of Channa lucius (Cuvier) and Channa striata (Bloch) from the Bukit Merah Reservoir, Perak and Endau-Rompin, Pahang, Peninsular Malaysia. They are Trianchoratus longianchoratus sp. n., T. malayensis Lim, 1986 and T. pahangensis Lim, 1986 from C. lucius, and T. ophicephali Lim, 1986 from C. striata. The new species differs from the Trianchoratus species hitherto described from channids and anabantoids in having two ventral anchors with a long curved inner root and one dorsal anchor with a curved inner root and lacking an outer root. A table summarizing the known species of heteronchocleidins (Trianchoratus, Eutrianchoratus and Heteronchocleidus) and Sundanonchus reported from fish hosts of different families (Channidae, Helostomatidae, Anabantidae and Osphronemidae) is provided.

The complete mitochondrial genome of Trichogaster microlepis was determined in this study. It is 16,435 bp in size and consists of 2 rRNA genes, 13 protein-coding genes, 22 tRNA genes and a non-coding control region (D-loop). The overall base composition of the heavy strand of the T. microlepis mitochondrial genome is A: 29.50%, T: 28.38%, C: 26.62%, and G: 15.49%. The total length of the 13 protein-coding genes was 11,427 bp. This study provides an important data set for the phylogenetic and taxonomic analyses of the Trichogaster species.

The complete mitochondrial genome of Trichogaster leeri is determined in this study. It is 16,454 bp in length and consists of 13 protein-coding genes, 2 rRNA genes, 22 tRNA genes and a non-coding control region (D-loop). The overall base composition of the heavy-strand (H-strand) of the T. trichopterus mitochondrial genome is A: 29.18%, T: 28.07%, C: 27.20% and G: 15.55%. The total length of the 13 protein-coding genes was 11,435 bp. Phylogenetic analysis showed that the species of Trichogaster (T. trichopterus, T. lalius and T. leeri) formed a monophyletic group and represented close relationship with the species of Anabantoidei. This study provides an important data set for phylogenetic and taxonomic analyses of the species of genus Trichogaster.

All fish species in the Anabantoidei suborder are aquatic air-breathing fish. These species have an accessory air-breathing organ, called the labyrinth organ, in the branchial cavity and can engulf air at the surface of the water to assist in gas exchange. It is therefore necessary to examine the extent of gill modification among anabantoid fish species and the potential trade-offs in their function. The experimental hypothesis that we aimed to test is whether anabantoid fishes have both morphological and functional variations in the gills among different species. We examined the gills of 12 species from three families and nine genera of Anabantoidei. Though the sizes of the fourth gill arch in three species of Trichogaster were reduced significantly, not all anabantoid species had morphological and functional variations in the gills. In these three species, the specific enzyme activity and relative protein abundance of Na(+)/K(+)-ATPase were significantly higher in the anterior gills as compared with the posterior gills and the labyrinth organ. The relative abundance of cytosolic carbonic anhydrase, an indicator of gas exchange, was found to be highest in the labyrinth organ. The phylogenetic distribution of the fourth gill's morphological differentiation suggests that these variations are lineage specific, which may imply a phylogenetic influence on gill morphology in anabantoid species.

The complete mitochondrial genome of Trichogaster trichopterus was determined in this study. It is 16,452 bp in size and consists of 2 rRNA genes, 13 protein-coding genes, 22 tRNA genes and 1 non-coding control regions (D-loop). The overall base composition of the heavy strand of the T. trichopterus mitochondrial genome is A: 29.50%, T: 28.36%, C: 26.62% and G: 15.49%. The total length of the 13 protein-coding genes was 11,427 bp. Analysis of the genes indicated the high genetic variability among Osphronemidae species.

Socially isolated Macropodus opercularis showed a distinct approach response to water taken from the tank of a conspecific individual or a nonconspecific, Trichogaster trichopterus, but not to water from a tank without fish. It is proposed that these species produce chemical stimuli which are attractive to M. opercularis. Approach frequency and the total duration of approach during a 10-rain period of stimulation varied with the species and the sex of the stimulus fish but not with the sex of the subject. Subjects responded most frequently to the conspecific male and nonconspecific female stimuli and, least to the nonconspecific male stimuli. Rossi (1969) reported that solitary male Macropodus opercularis (family, Belontiidae; subfamily, Macropodinae) show increased nest building and aggressivity in response to female chemical stimuli. Observations in this laboratory during various experiments on social behavior (Davis, Harris, and Shelby, 1974) confirm that mature 34. opercularis respond to chemical cues from species mates. Water that has contained a female for a period of days can elicit immediate arousal consisting of erection of the medial fins and striking changes in skin color in an isolated male. These are elements of the species-typical responses which are seen in courtship and nest defense (Forselius, 1957; Ward, 1967). In addition, in a situation in which female stimulus water is" added slowly through a tube at the water surface, fish approach the incurrent tube and investigate the opening. The approach response occurs even when the behavioral arousal response does not, as when the stimulus is diluted with fresh water prior to entering the tank. 1We thank Jessie Shelby for her valuable technical assistance. 2Liem's classification of the order Anabantoidei into four families is preferred because it presents a more convincing hypothesis of the natural relationships between the divergent species in this group than does the older classification of Regan (1906).

Description d’un nouveau Camallanidae ; Camallanus ctenopomae n. sp. parasite de Ctenopoma kingsleyae Poisson Anabantidae du Senegal. Cette espece differe des autres Camallanus par les caracteres de sa capsule buccale, de ses spicules et de ses extremites caudales mâle et femelle.

Testicular tissues of Betta picta, Betta smaragdina , and the short-finned variety of Betta splendens were incubated with [ 14 C]testosterone at 27° for 120 min and the metabolites were isolated and characterized by paper and thin-layer chromatography and eventually by crystallization to constant specific activity. The metabolic profiles of the species were totally different. The short-finned B. splendens formed mainly 11-ketotestosterone (51.4%) as does the veiltail variety. B. smaragdina was the only species which formed considerable amounts of conjugates (24.3%), whereas in B. picta almost exclusively reduced (β-) compounds (66.2%) were metabolites of testosterone. The results are discussed to be attributable to differences in testicular steroid metabolism. The significance of this observation remains unclear.

Testicular tissues of the Siamese fighting fish were incubated with [14C]pregnenolone for 10, 20, 30, 50, 80, and 120 min, and with [14C]progesterone, [14C]11 beta-hydroxyandrostenedione, [14C]11 beta-hydroxytestosterone, and [14C]androstenetrione for 120 min. 11-Ketotestosterone was the main metabolite in all 120-min incubations. No 11-oxygenated C21 steroids were found as metabolites of either pregnenolone or progesterone. The biosynthesis of 11-ketotestosterone proceeded through both the delta 5- and the delta 4- pathways as judged from the shape of the yield-time curves of the metabolites of pregnenolone. 11-Ketotestosterone formation from 11-oxygenated precursors increased in the order 11 beta-hydroxytestosterone less than 11 beta-hydroxyandrostenedione less than androstenetrione.

Minced testes of the Siamese fighting fish Betta splendens were incubated with [14C]androstenedione at 27 degrees C for 15, 30, 60, and 120 min. The metabolic products were characterized by paper and thin-layer chromatography, derivative formation, and eventually by crystallization to constant specific activity. After 2 hr of incubation 80.5% of total radioactivity was converted to 11-oxygenated androgens. 11-Ketotestosterone was the main metabolite (56.2%). Our data suggest the existence of two biosynthetic pathways for the formation of 11-ketotestosterone from androstenedione. The sequence androstenedione----testosterone----11 beta-hydroxytestosterone----11-ketotestosterone predominates. To a lesser extent 11 beta-hydroxylation takes place as the first step--followed by formation of 11 beta-hydroxytestosterone and its subsequent oxidation to 11-ketotestosterone.