Animal agonistic behaviors, including threat, combat, submission and chase, are complex responses to experimental stimuli. Animal behaviors are regulated by the central nervous system. In the central nervous system, the biogenic amine serotonin has been thought to serve important roles in animal aggression (including fish), but it¡¦s not clear if serotonin affects threatening and fighting differently. This study took experimental approaches to examine the effects of this neurotransmitter on threatening and fighting in a paradise-fish model in which the complex agonistic behavior is well characterized. Treatments with serotonin synthesis precursor tryptophan (0.125mg/g) to one of the two contestants had insignificant effects on threatening or fighting while synthesis blocker p-Chlorophenylalanine (PCPA) (0.3mg/g) decreased threatening time and occurrences of head-tail display. When these drugs were added to both contestants, tryptophan reduced all agonistic behavioral patterns displays, and PCPA decreased threatening time and head-tail display. In addition to changes in behavioral patterns, tryptophan led the fish to be attacked. In contrast, PCPA led the injected fish to actively attack its opponent. However, tryptophan and PCPA had no effect on social status in parasise fish. I suggest that agonistic responses and the initial fighting decision in a paradise fish are affected not only by level of its serotonin, but also by the behavioral responses of its opponent. And the establishment of outcome of encounter is affected more by the environmental stimuli than the serotonin level.

1. Institute of Marine Biology, National Sun Yat-sen University 2. Department of Biology, National Changhua University of Education Abstract Brain serotonin (5-hydroxytryptamine; 5-HT) generally serves an inhibitory role in aggressive behavior. But little is known about how 5-HT works during agonistic interaction and where the related works take place in the brain. Paradise fish has regular and ritual process of agonistic interaction which can be separated into three phases, namely, initial phase, threatening phase, and fighting phase. In initial phase, two fish encounter and swim close to each other. In threatening phase, two fish display shaking, head-tail swimming to threat their opponent. In fighting phase, two fish bite each other. With its stereotyped pattern of agonistic behaviors and amenability for pharmacological manipulation, paradise fish represents an excellent model for studies on neurochemical basis of aggressive behaviors. The results suggested that proper visual stimulus stemming from the interacting opponents elicits a socially stressful state that activates the telencephalic serotonergic system of the receipting paradise fish. The elevated serotonergic activity appears to inhibit the interacting individuals from entering fighting phase by constraining them to threatening phase. Presumably, diminishing activity of the telencephalic serotonergic system ushers in physical fighting behaviors.

The development of Sacropodus opercularis Linnaeus, (Perciformes: Anabantidae), is described from cleavage to five days post hatching. For the most part M. opercularis follows the pattern of typical teleostean development except as noted below: 1. The heart develops under the left eye along the anterior margin of the yolk sac. This is similar to that reported by Ingesoll (1951) for the Blue Gourami, Trichogaster trichopterus. 2. The ear develps from the head mesenchyme alongside the brain rather than from a placode. 3. The gut develops first in the posterior region then differentiates cephalad. It was also learned that: 1. No true bone exists in the skeletal system up to five days of development post hatching at 80°F. 2. The hatching time was 35-37 (36) hours after fertilization at 80°F.

The purpose of this paper is to critically study and analyze all species belonging to the genus Pantosteus and to determine tbe validity of the characteristics that were used to separate the genus Notolepidomyzon from the genus Pantoateus. Special reference was made to the morphology of the fontanelle and the weberian ossicles. In order to more thoroughly comprehend the reasons for Cope describing Pantosteus as a new genus and Fowler describing Notolepidomyzon as a new sub-genus and then Snyder elevating it to the status of a genus as complete a historical sketch as possible was made using all literature known and available. A description has been made of the genus, the sub-genera, and all species concerned in this study. The two critical factors which separate the genus Notolepidomyzon from the genus Pantosteus received special attention. Illustrations showing the structure of the cranium have been made of representative specimens of all species except P. generosus. The fontanelle remained constant in some species, but in others it varied greatly. The weberian ossicles vere studied and illustrations made or species within both genera. No definite critical factor could be found with the ossicles that could be used to separate the genera. It is the proposal of the writer that since the characteristics that were used to distinguish these two genera are not consistent nor completely reliable, the genus Notolepidomyzon not be recognized as separate genus, but retained as a sub-genus distinguished from the sub-genus Pantosteus primarily on the thickness of the cranium and the open or obliterated fontanelle. The material and evidence needed to support this proposal is contained in this paper.