Morphometric analysis of otoliths of juvenile crucifix sea catfish Sciades proops (Valenciennes, 1840)

The objective of this study was to analyze the morphometry of otoliths for Sciades proops juveniles by testing the hypothesis of equality in morphometric relationships for the right and left otoliths, which could then be interchangeably used to estimate fish size or weight. Samples were obtained monthly directly from anglers after each event that took place off the state of Sergipe from March/2014 to April/2015. Anglers used rod and reel during these events, with no restriction on hook size or line thickness. Each fish specimen sampled had their total weight (W, g) and total length (TL, cm) measured and their lapillus otoliths removed and stored separately. Each otolith had its length (OL), width (OWi), and thickness (OT) measured (all in mm) under a stereomicroscope. Otoliths were weighed using a precision scale (OW, g). A total of 883 specimens were sampled: TL = 12.0–60.5 cm and W = 9.8–1880 g. The weight‐length relationship for the juvenile fishes was W = 0.0052TL^3.086 and for their otoliths was OW = 0.0002OL^3.177. The weight‐length and length‐length relationships fitted for each otolith (right and left) were not statistically different and thus all relations were estimated for grouped otoliths. The length‐length relationships for the otoliths were: OWi = 0.947OL?0.205 and OT = O.484OL?0.698. The relationship estimated for juvenile fish and otolith weight was Wj = 1076.1OW?9.120. For juvenile fish total length and otolith length, width and thickness, the following relationships were estimated: TLj = 4.028OL?3.199, TLj = 4.208OWi?2.091, and TLj = 7.824OT + 3.659, respectively. Relationships between fish and otolith size, and between fish and otolith weight indicated a change in slope close to L_m50, which should be better explored when more adult specimens are available.     

Photoresponse ontogeny and its relation to development of pineal organ and eye in larval bagrid catfish Mystus nemurus (Valenciennes)

The artificially reared bagrid catfish Mystus nemurus was observed for the histological development of the pineal organ and retina and photoresponse in a test tank at hatching to 14?d after hatching. The pineal organ was functional at hatching, and the lens-like tissue was partly ossified forming a pineal window at 6?d. The retina became morphologically functional when the outer segments of single cones were formed, and the eyes were innervated with the optic tectum at 18?h and rods were formed at 36?h. Long and thin single cones were not observed. The larvae exhibited undirected kinetic movement at hatching to 12?h and directed tactic swimming away from a torch after 18?h in response to a torch light. The photoresponse of the larvae was negative at hatching to 30?h and at 6?d to the end of the observation at 14?d, but neutral during a period at 36?h to 5?d. It was evident that the kinetic movement was mediated by light perception with the pineal organ, which was not capable of detecting directed signal information, and that the larvae were capable of directed tactic movement only when vision was involved. The vigorous negative phototaxis at 6–14?d was attributed to the improvement of photosensitivity of the retina and the pineal organ.     

Characterization of feeding habits,prey diversity and diet overlap of two sympatric species: Bronze catfish,Netuma bilineata (Valenciennes, 1840) and blacktip sea catfish,Plicofollis dussumieri (Valenciennes, 1840) in the northern Arabian Sea

This study describes the diet composition, diet overlap and prey diversity in two economically and ecologically important marine catfish species: the bronze catfish (Netuma bilineata) and the blacktip sea catfish (Plicofollis dussumieri) collected between January and December 2015 from the northern Arabian Sea coast of Pakistan. Stomach data of 342 bronze catfish and 283 blacktip sea catfish were examined. Diet composition and feeding strategy of each species by identification of stomach contents were weighed and enumerated. Both species primarily consumed teleosts, Brachyura and small amounts of a wide variety of prey items; however, specialization was a more common trait for the bronze catfish than for the black tip sea catfish. The Morisita‐Horn index showed considerable diet overlap in percentage of mean weights (0.847) than in numbers (0.612) between co‐prey pairs of both species. The highest Bray‐Curtis similarity between the southwest monsoon (SWM) and south inter monsoon (SIM) was observed in bronze catfish and lowest between autumn inter monsoon (AIM) seasons in both species. While Bray‐Curtis dissimilarity was observed, both species share diet niches and diet overlap. The present study evaluation of the feeding strategy and potential competition between two sympatric species of marine catfishes can provide the framework for their conservation and management in the region.     

Growth and survival of river catfish Mystus nemurus (Cuvier & Valenciennes) larvae fed isocaloric diets with different protein levels during weaning

The growth of river catfish Mystus nemurus (Cuvier & Valenciennes) larvae fed four isocaloric diets (4200 kcal kg^?1) with different protein levels during weaning was determined. Diets containing 45, 50, 55, and 60% protein were formulated by linear programming using amino acid profiles based on that of 2‐day‐old river catfish larvae. Artificial diets were fed to the larvae beginning at day 5 after being initially fed Artemia nauplii for 4 days. The larvae thrived solely on artificial diets from day 8 to day 16. On the other hand, the control larvae were fed Artemia nauplii from day 1 to day 16. Results of the feeding trial showed that growth and survival of M. nemurus larvae given the diet containing 60% protein were high and comparable to those of the larvae given only live food (control). Larvae fed the 55% protein diet had significantly lower growth and survival than the larvae on the control and 60% diets but significantly higher growth and survival rates than did larvae fed with 45 and 50% protein diets. Carcass moisture and total lipids after 16 days of feeding did not differ significantly (P > 0.05), but body protein increased with increasing dietary protein. Body protein of the control larvae was similar to that of larvae given the 60% protein diet.     

Population structure of the Southeast Asian river catfish Mystus nemurus

A total of 143 microsatellites were isolated from Mystus nemurus using a 5' anchored polymerase chain reaction technique or the random amplified hybridization microsatellite method, the first set of microsatellite markers developed for the Southeast Asian river catfish. Twenty polymorphic microsatellite loci were used as markers for population characterization of M. nemurus from six different geographical locations in Malaysia (Perak, Kedah, Johor, UPM, Sarawak and Terengganu). The number of alleles per locus ranged from 2 to 11 with 6.3 as the average number of alleles per locus. Characterization of the populations showed relatively high levels of genetic variation compared with previous studies using allozyme markers. The highest genetic similarity was found between Perak and Kedah, while the highest genetic distance was found between Terengganu and Kedah. The majority of clustering was in accordance with geographical locations and the histories of the populations. Microsatellite analysis indicated that the Sarawak population might be genetically closer to the Peninsular Malaysian populations than has been previously shown by other molecular marker studies.     

Myxosporean parasites of the catfish,Clarias lazera (Valenciennes)

Summary Five new species of myxosporean were found in the catfish Clarias lazera (Val.) in Israel. These species are described as: Henneguya laterocapsulata n. sp. (cyst-like trophozoites in the skin), H. suprabranchiae n. sp. (cyst-like trophozoites in the suprabranchial respiratory organs), Sphaerospora inaequalis n. sp. (spores in the lumen of the kidney tubules), Myxidium clariae n. sp. (spores in the gall bladder) and Myxobolus heterofilamentatus n. sp. (spores in the kidney, spleen, liver, suprabranchial respiratory organ, gills, heart and urinary bladder). Their taxonomic affinities to other species are discussed. ac]19860407     

Myxozoan pathogens in cultured Malaysian fishes. II. Myxozoan infections of redtail catfish Hemibagrus nemurus in freshwater cage cultures

Cage-cultured Asian redtail catfish Hemibagrus nemurus (Valenciennes, 1840), a popular food fish in Southeast Asia, proved to be infected by 3 myxozoan species. All the 3 species belonged to the genus Henneguya: 2 were identified as H. mystusia Sarkar, 1985 and H. hemibagri Tchang et Ma, 1993, while the other was described as H. basifilamentalis sp. n. All plasmodia were found in the gills and were characterised by a specific site selection. H. mystusia formed plasmodia in the multi-layered epithelium between the gill lamellae and in the non-lamellar edge of the gill filaments, while H. hemibagri developed in the capillary network of the lamellae. H. basifilamentalis sp. n. had large oval plasmodia located deep among the filaments just above the gill arch.     

The South American catfish genus Auchenipterus Valenciennes, 1840 (Ostariophysi: Siluriformes: Auchenipteridae): monophyly and relationships, with a revisionary study

The Neotropical catfishes of the genus Auchenipterus Valenciennes (1840) are reviewed. The genus is hypothesized to be a monophyletic assemblage on the basis of the shared presence of grooves in the ventral surface of the head that accommodate adducted mental barbels. A possible second synapomorphy, the presence of papillae on the dorsal and medial surface of the ossified maxillary barbel of mature males, is tentatively advanced pending discovery of adult males of three species. Contrary to previous hypotheses which considered Auchenipterus to consist of a maximum of five species, we recognize 11 species, including two previously undescribed forms, A. britskii and A. menezesi: Auchenipterus is broadly distributed through the Rio Orinoco, Rio Amazonas, and Rio de La Plata basins, and the coastal drainages of the Guianas, with one species in the Rio Pindare-Mirim and Rio Parnaiba basins of northeastern Brazil. Auchenipterus nuchalis, previously thought to be broadly distributed across the range of the genus, is found to rather have a restricted distribution in the eastern portions of the Amazon basin, the lower portions of the Rio Tocantins, and lower courses of some rivers in Suriname and French Guiana. Citations of A. nuchalis from elsewhere in the range of the genus are of other species. Euanemus Müller & Troschel (1842) and Ceratocheilus Miranda Ribeiro (1918) are considered synonyms of Auchenipterus. Euanemus colymbetes Müller & Troschel (1842) is considered a synonym of Auchenipterus (fen/ata Valenciennes (1840), and A. paysanduanus Devincenzi (1933) is placed into the synonymy of A. nigripinnis Boulenger (1895). A neotype is designated for Hypopthalmus nuchalis Spix & Agassiz (1829). Lectotypes are designated for Euanemus colymbetes and Auchenipterus nigripinnis.     

Isolation and characterization of microsatellites in the Southeast Asian river catfish Mystus nemurus

A total of 26 simple sequence repeats were identified using a random amplified polymorphic DNA (RAPD) based technique in the Southeast Asian river catfish Mystus nemurus. We report on the characterization of five polymorphic microsatellite loci in M. nemurus. The average number of alleles per locus was 3.2. These are the first microsatellite loci that have been developed for this species. These markers should prove useful as tools for managing the brood stocks and for future aquacultural development of this species.     

Phylogeography of the African catfish,Chrysichthys maurus (Valenciennes, 1839)

Polymorphism at 19 allozyme loci was studied in 227 individuals of the catfish, Chrysichthys maurus (Valenciennes, 1839), collected from ten populations representing nine different river basins in west Africa. Eleven of the loci studied were polymorphic. Analysis showed that populations clustered according to their geographical origin: eastern populations close to the root represented by a population of a closely related species (C. auratus); then populations from the centre of the species' range, followed by the more western populations. Networks observed, regression of genetic distances versus geographical distances, results of the Mantel test as well as the apomorphic status of two alleles suggested that the genetic differentiation corresponds to an isolation by distance model. These results strongly suggest that the populations initially occurred in the lagoons and rivers of Ivory Coast and from here spread to the western part of the species' range by progressively colonising basins from east to west.     

Establishment and cryopreservation of a cell line derived from caudal fin of endangered catfish Clarias dussumieri Valenciennes, 1840

We describe a new cell line, Clarias dussumieri fin (ClDuF), from the caudal fin of C. dussumieri using the explant technique followed by cryopreservation. The cryopreserved CiDuF cells were validated for quality and other characteristics. They showed typical epithelial morphology in vitro and epithelial cells outgrew their fibroblast cells after the fifth passage. ClDuF cells had a characteristic sigmoid curve with population doubling in 24 h. Immunotyping of the ClDuF cells against cytokeratin suggested the epithelial lineage. Chromosome analysis showed normal diploid (2n = 50) numbers and the cells did not contain any contamination, including Mycoplasma and other microbes. Partial sequencing of fragments of mitochondrial 16s rRNA and COI genes of ClDuF confirmed that the cell line was initiated from C. dussumieri. Cells at the 10th and 25th passages had more than 80% and 70% viability in the culture, respectively, after 6 months of storage at LN₂. These ClDuF cells were morphologically identical to the cells before freezing and the genetic resource of C. dussumieri was preserved. The species-specific cells can serve as a valuable source for virus isolation, conservation and cloning of somatic cells.     

Phylogeographic structure in mitochondrial DNA of a South-east Asian freshwater fish, Hemibagrus nemurus (Siluroidei; Bagridae) and Pleistocene sea-level changes on the Sunda shelf

We postulated that the biogeographical history of South-east Asia contributed to extensive admixture during Pleistocene low sea levels of genetic groups of an obligate freshwater fish (the river catfish, Hemibagrus nemurus) isolated during periods of high sea levels. During Pleistocene glacial maxima, the sea level was lower than at present and the islands of the Sunda shelf (Sumatra, Borneo and Java) and the Asian mainland were connected by lowlands traversed by rivers. Restriction fragment length polymorphisms in mitochondrial DNA were documented for 140 putative H. nemurus analysed from 13 sampling sites resulting in the definition of 35 haplotypes. The high level of haplotype differentiation (mean P × 100 = 2.22, SD = 1.33) indicates that the subdivision of the ancestral H. netnurus group was extensive and probably occurred early in the Pleistocene. The occurrence of some genetically divergent groups of the H. netnurus complex occurring in sympatry in widely separated locations supports the proposition that low sea levels aided the dispersion and mingling of genetic groups. Based on both genetic and morphological evidence, the main H. nemurus line gave rise to three regional groups: (1) a morphologically distinct ‘Indochinese’ group composed of two mtDNA clades overlapping in east peninsular Malaysia; (2) a ‘Sundaic’ group composed of various lineages of differing morphology and genetic identity; (3) a genetically distinct ‘Sarawak’ group in west Borneo, similar in morphology to the ‘Sundaic’ and ‘Indochinese’ groups, but including a small, golden colour morph as a distinct dade. The morphologically similar Sundaic forms from west Java, Sumatra and west Borneo show some degree of genetic divergence, but their phylogenetic relationships are poorly resolved. The most genetically and morphologically distinct Sundaic dade, assigned to H. hoevenii, colonized the Kapuas river (west Borneo), east Sumatra and south peninsular Malaysia. Contrary to our original hypothesis and present biogeographical theory, little exchange of genetic groups has apparently occurred between the mainland and the Sunda Islands during recent glaciations.     

Genetic identification of bucktooth parrotfish Sparisoma radians (Valenciennes, 1840) (Labridae,Scarinae) by chromosomal and molecular markers

Parrotfishes (Labridae, Scarinae) comprise a large marine fish group of difficult identification, particularly during juvenile phase when the typical morphology and coloration of adults are absent. Therefore, the goal of this study was to test cytogenetic markers and DNA barcoding in the identification of bucktooth parrtotfish Sparisoma radians from the northeastern coast of Brazil. Sequencing of cytochrome c oxidase subunit I (COI) confirmed all studied samples as S. radians, and all showed high similarity (99–100%) with Caribbean populations. The karyotype of this species was divergent from most marine Perciformes, being composed of 2n = 46 chromosomes. These consisted of a large number of metacentric and submetacentric pairs with small amounts of heterochromatin and GC-rich single nucleolar organizer regions (NORs) not syntenic to 5S rDNA clusters. These are the first data about DNA barcoding in parrotfish from the Brazilian province and the first refined chromosomal analysis in Scarinae, providing useful data to a reliable genetic identification of S. radians.     

Ovarian activity of Agouti paca (Rodentia: Agoutidae) under captivity

The ovarian activity of Agouti paca was characterized by hormonal profiles and ovarian structures. Samples of blood were taken from eight females (seven adults and one juvenile) at the breeding grounds of the Facultad de Medicina Veterinaria y Zootecnia in Yucat?n, Mexico. Sampling lasted approximately two months and was done every three and six days. Blood was collected from anesthetized animals, and the levels of progesterone (P4) and 17 beta estradiol (E2) were analized by radioimmunoassay technique. Macroscopic and microscopic analyses were carried out in ovaries of dead animals. The estrous cycle lasted 29+/-8.4 days, levels of 1.61+/-0.65 ng/ml for P4 and 39+/-24 pg/ml for E2 were observed for a follicular phase, 6.18+/-3.70 ng/ml and 29+/-16 pg/ml for P4 and E2 respectively in the luteal phase. Statistically significant differences were found between phases for P4 but not for E2. The presence of extragonadal steroids with levels of P4 of 1.9+/-0.77 ng/ml and E2 of 22+/-17 pg/ml were observed, which are not produced by the effects of managing stress. The changes in the levels of P4 during the cycle are indicators of luteal activity, with the intersticial tissue acting probably as active steroids-producing gland. Follicular growth was observed during the entire cycle.     

Behavioral development of a polar bear cub (Ursus maritimus) in captivity

The difficulty of observing polar bears (Ursus maritimus) in the wild has prohibited the gathering of behavioral data necessary to develop a baseline set of milestones for monitoring cub development. This study describes and quantifies previously undocumented trends in behavior observed in a captive cub–information that will be useful both in future comparative studies and in the implementation of husbandry improvements. Nearly 400 hr of behavioral data were collected, 100 hr of which were video recordings from the maternity den during the first 3 months of life. Den videos were scored to determine activity budgets and levels of maternal contact. For the remainder of the first year, mother and cub were observed in the outdoor enclosure. The onset and relative frequency of 40 discrete cub behaviors were tracked, as were patterns of mother–cub contact, including nursing and weaning. This study revealed that environmental conditions, habitat enrichment, and conditioning procedures influenced the patterns of developmental behavior exhibited by a polar bear cub. Both climatic and developmental factors had significant effects on the time the bears spent swimming. Management practices, such as environmental enrichment, and a conditioning procedure involving separation of mother and cub caused transient changes in several tracked behaviors. As the cub aged, the longest time between consecutive maternal contacts increased. Nursing bouts recorded per hour of observation decreased, and the duration of individual nursing bouts and pre‐nurse begging periods increased. Zoo Biol 22:507–514, 2003. © 2003 Wiley‐Liss, Inc.     

A karyological analysis of the artificial hybridization between Clarias gariepinus (Burchell, 1822) and Heterobranchus longifilis Valenciennes, 1840 (Pisces; Clariidae)

A karyological analysis of an artificial hybridization (reciprocal crosses) between two African clariid catfish, Clarias gariepinus (Burchell, 1822) and Heterobranchus longifilis Valenciennes, 1840, was performed. C. gariepinus has a standard karyotype of 2 n = 56, while H. longifilis has 2 n = 52. The hybrids revealed an intermediate karyotype (2 n = 54), and it appears as if they have totalized the haploid chromosome number of both parental species, excluding gynogenesis or androgenesis. The hybrid karyotype is considered as aneuploid, although the hybrids proved to be fertile. No variation was found in the hybrids karyotypes.