Early Ontogeny of the Climbing Perch Anabas testudineus (Anabantidae) in Relation to the Buoyancy Dynamics

Journal of Ichthyology - This article describes early development of the climbing perch Anabas testudineus in relation to its buoyancy dynamics. Main patterns of the ontogeny during the first 140 h...     

Reproduction and spawning behavior of the climbing perch Anabas testudineus (Perciformes, Anabantidae) in an aquarium

Results of study of the spawning and reproductive behavior of the climbing perch Anabas testudineus in an aquarium are presented. Main specific features of reproduction of this species are revealed. In the performed experiments, climbing perches did not build a nest, did not prepare a spawning substrate, and did not show any forms of parental care. The pre-spawning and spawning behavior of the climbing perch is described, and fecundity and gonadosomatic index are determined. It is shown that intermittent spawning is typical of these fish. Mating system of the climbing perch is either polygamy or promiscuity. Sexual dimorphism in the climbing perch was not found. The eggs of the climbing perch have positive buoyancy and belong to the really pelagic type, which is rare for freshwater fish. Infanticide is a common phenomenon for the climbing perch. Breeding of the given species under aquarium conditions can be exercised without artificial hormonal stimulation, at different sex ratio, and under conditions of stocking density considerably exceeding standard aquacultural recommendations. The main specific features of reproduction of the climbing perch are discussed in relation to evolution of parental care in labyrinth fishes.     

Dietary supplementation of essential fatty acids in larval pikeperch (Sander lucioperca); short and long term effects on stress tolerance and metabolic physiology

The present study examined the effects of feeding pike perch larvae Artemia, enriched with either docosahexanoic acid (DHA), arachidonic acid (ARA), oleic acid (OA), olive oil (OO) or a commercial enrichment DHA Selco (DS) on tissue lipid deposition, stress tolerance, growth and development, and metabolic rate. There was higher tissue retention of ARA than DHA at comparable inclusion levels. No differences were observed between diets on the percentage contribution of ARA or DHA to the fatty acid profile of tissues (head and trunk). Total fatty acid content (mgg(-1)) was significantly higher in the head, reflecting its high content of neural tissue. Observations on larval erratic behaviour and mortality following exposure to salinity stress suggested that high inclusions levels of DHA had an alleviating effect, while ARA did not. Particularly larval groups reared for 16 days on diets enriched with OO and OA had mortality rates approaching 100% within two hours. Interestingly, this tendency, although not as pronounced, was also apparent in juvenile fish after 120 days of rearing on a common diet. Standard metabolic rate in larvae on an OO enriched diet was significantly elevated, but otherwise no groups had significant changes to their respiratory physiology. In addition to increased stress challenge sensitivity, early feeding with OA had long term impact on pike perch neural development indicated by a smaller brain size in juvenile fish. In conclusion, lack of DHA in the diet of pikeperch larvae suggests that this long chain polyunsaturated fatty acid is involved in processes that increase stress tolerance and that lack of dietary DHA in early larval stage caused increased stress sensitivity and long-term impaired neural development, while it does not appear to affect metabolic rate at rest.     

Feeding,development, and growth of juvenile perch <Emphasis Type="Italic">perca fluviatilis</Emphasis> in mesocosms in the presence of filter-feeding zebra mussel <Emphasis Type="Italic">Dreissena polymorpha</Emphasis> pallas

Quantitative and qualitative changes in the feeding spectra and growth patterns are studied in the larvae and juveniles of perch in artificial water ecosystems (mesocosms) in the presence of a filter-feeding zebra mussel. At a stocking density of 0.75 kg/m², the presence of a zebra mussel leads to a change in the feeding conditions of zooplankton, to a decrease in its abundance in regards to critical values for fish feeding, to an increase in the abundance of organisms of macrobenthos in the food, and to the rapid transition of the fish to feeding on chironomids. As a result of these changes, the growth rate of perch larvae decreases, their development at step D ₁ is delayed, the differentiation of the juveniles by size is accelerated, their size and weight variability increases, and individual predators (cannibals) appear.     

Seasonal transmission ofRaphidascaris acus (Nematoda), a parasite of freshwater fishes,in definitive and intermediate hosts

Synopsis The seasonal transmission ofRaphidascaris acus was studied in two small lakes on Manitoulin Island, Ontario. Dragonfly nymphs and caddisfly larvae, acting as paratenic hosts, contained second-stage larvae. Several fishes, including percids and cyprinids, were intermediate hosts with second, third, and fourth-stage larvae in the liver. Yellow perch,Perca flavescens, was the most important of these. Intensities were up to 928 and increased with length and age of the perch; prevalence was 100%. Abundance ofR. acus tended to be higher in females but was not related to condition of the perch. Second-stage larvae were acquired from invertebrates in summer and developed to the fourth stage by November. They became surrounded by fibrous capsules during the next summer but remained alive for at least another year. The longevity of larvae in the intermediate host may ensure survival of the parasite through periods of low host abundance after winterkill. Northern pike,Esox lucius, was the definitive host. Abundance ofR. acus tended to be greater in larger pike but was not related to sex or condition of the fish. The parasite was acquired in late fall. Prevalence was 100% and mean intensities were over 200 in winter and spring, declining to 64–100% and less than 15, respectively, in summer. Mature worms were present from early spring through summer. Seasonality of infection in the definitive host is not attributable to seasonal availability of larvae in perch. Instead it may be controlled by timing of predation on perch and rate of development and longevity of the parasite. Transmission to pike apparently continues in summer. Low intensity may result from low recruitment rate and rapid turnover of the parasite population.     

The role of ecotones as feeding grounds for fish fry in a Bohemian water supply reservoir

The food composition of young-of-the-year (YOY) roach, common bream and perch, the dominant fish species in ímov reservoir, was investigated during 1989 and 1990. The littoral fry assemblages were dominated by roach and perch, while bream larvae migrated into deeper water early in their development. The YOY roach fed opportunistically. Up to 15 mm length they remained close to the shoreline, preferring periphyton, Chydoridae and larval Chironomidae. Perch larvae between 10–15 mm long gradually became demersal but their diet continued to consist of the planktonic Cyclops spp. and Diaptomus spp. Resource partitioning was a characteristic feature of the littoral fry assemblages. The only significant overlap in diet occurred with Polyphemus pediculus, which was positively selected by both roach and perch fry.     

Growth and morphological development of laboratory-reared larval and juvenile climbing perch <Emphasis Type="Italic">Anabas testudineus</Emphasis>

Morphological development, including fin and labyrinth organ, body proportions and pigmentation, in laboratory-reared larval and juvenile climbing perch Anabas testudineus was described and behavioral features under rearing condition were observed. Body lengths (BL) of larvae and juveniles were 1.9 ± 0.1 (mean ± SD) mm just after hatching (day-0), 8.7 ± 1.3 mm on day-19, reaching 18.4 ± 2.1 mm on day-35 after hatching. Aggregate fin ray numbers attained full complements in juveniles larger than 8.3 mm BL. Preflexion larvae started feeding on day-2 following formation of the upper and lower jaws, the yolk being completely absorbed by day-7 after hatching. Teeth appeared in flexion larvae larger than 5 mm BL on day-6, with cannibalism starting shortly after and continuing with further growth. Melanophores on the body increased with growth, a large dark spot developing on the lateral midline around caudal margin of the body in the postflexion and juvenile stages. The labyrinth organ differentiated in postflexion larvae larger than 7.2 mm BL on day-16, with air-breathing starting at the same time. Body proportions attained constant in postflexion larvae larger than 7.0 mm BL, and habitat of fish shifted from bottom to mid-layer. With the exception of fin ray numbers, the above morphological developments corresponded to behavioral shifts that occurred in the postflexion stage (ca. 7 mm BL), their subsequent continuity illustrating that the species possessed most juvenile-equivalent functions from ca. 7 mm BL.     

千年笛鲷早期发育及视蛋白基因表达规律分析

初步观察千年笛鲷早期发育各个时期的形态特征, 同时使用实时荧光定量PCR方法对4种视蛋白基因在早期发育中的表达规律进行分析。研究观察到千年笛鲷卵为圆球形, 属浮性卵, 中心有一明显的油球。在水温(24.50.5)℃的条件下, 千年笛鲷胚胎发育共经历6个发育阶段18个时期, 从受精卵到孵化一共经历24h。仔鱼经历1215d发育为稚鱼, 30d35d发育为幼鱼。同时对7个胚胎发育时期和2个仔鱼发育时期4种视蛋白(LWS、SWS1、SWS2、RH)基因的表达情况进行检测, 在下包1/2、胚孔封闭、视囊这3个时期有显著性表达(P0.05), 尤其在胚孔封闭时期, 表达量达到最高。其余时期4种基因的表达水平显著下降, 但在2个仔鱼时期表达量比孵化期略有增加。结果表明千年笛鲷4种视蛋白基因在早期表达过程中与神经胚的形成有密切的联系。       

Competition,predation, cannibalism: the development of young‐of‐the‐year perch populations in ponds with bream or roach

Piscivory of perch can occur within a few weeks after perch hatch, leading to the development of two size‐cohorts, with the larger perch becoming cannibals. However, the possibility of early piscivory is assumed to depend on the hatch timing of the prey and predator. Two species, bream (2006) and roach (2007), were tested as the prey fish. The bream (hatching 12 days after perch) were preyed upon by the perch, leading to the predicted development of two sizes of cohorts as well as to cannibalism. With roach (hatching simultaneously with perch), however, no piscivory or cannibalism occurred and the perch population was unimodally distributed. The results of this experimental pond study underpin recent theoretical findings that size differences between predator and prey, determined through differences in the timing of hatching as well as differences in juvenile growth rates, foster the occurrence of early piscivory in YOY perch that may lead to bimodality and finally to intra‐cohort cannibalism.     

Direct Estimation of Food Consumption of Juvenile Fish in a Shallow Inlet of the Southern Baltic

The species composition and feeding behaviour of fish larvae and juveniles was investigated in a shallow inlet of the Southern Baltic. The aim of the study was to examine if there was a predatory impact of young fish on the observed annual collapse of the copepod population. Dominant fish species were herring (Clupea harengus), perch (Perca fluviatilis) and roach (Rutilus rutilus). Roach larvae preferred shallower areas, whereas young herring and perch were found in open water. Highest consumption values were always observed in the evening. By computing complete evacuation of the digestive tract in approximately 3.5 hours, daily consumption in percent of fish fresh weight was 1.3, 4.7 and 5.5% for young herring, roach and perch, respectively. The impact of young fish on the dynamics of the population of the copepod species Eurytemora affinis is negligible.     

Growth of Perca fluviatilis larvae fed with Artemia spp. nauplii and the effects of initial starvation

Experiments were performed to test the growth and survival of perch larvae fed with Artemia spp. nauplii and to determine the most advantageous time of first feeding. During a first experiment, perch larvae were divided into groups according to their hatching dates. Daily ingestion of Artemia spp. nauplii began significantly 2 days after mass larvae hatching. By day 7, the daily prey acceptance was over 75% among the separate larvae groups. During a second 14-day feeding experiment, larvae fed after a 2- or a 3-day delay showed the best growths: 12.5 mm and 13.7 mg. There was no significant difference (P > 0.05) among survival rates (85.3%) of perch larvae fed after a 1-, 2- or 3-day delay.     

Mechanisms of Egg Yolk Formation and Implications on Early Life History of White Perch (Morone americana)

The three white perch (Morone americana) vitellogenins (VtgAa, VtgAb, VtgC) were quantified accurately and precisely in the liver, plasma, and ovary during pre-, early-, mid-, and post-vitellogenic oocyte growth using protein cleavage-isotope dilution mass spectrometry (PC-IDMS). Western blotting generally mirrored the PC-IDMS results. By PC-IDMS, VtgC was quantifiable in pre-vitellogenic ovary tissues and VtgAb was quantifiable in pre-vitellogenic liver tissues however, neither protein was detected by western blotting in these respective tissues at this time point. Immunohistochemistry indicated that VtgC was present within pre-vitellogenic oocytes and localized to lipid droplets within vitellogenic oocytes. Affinity purification coupled to tandem mass spectrometry using highly purified VtgC as a bait protein revealed a single specific interacting protein (Y-box binding protein 2a-like [Ybx2a-like]) that eluted with suramin buffer and confirmed that VtgC does not bind the ovary vitellogenin receptors (LR8 and Lrp13). Western blotting for LR8 and Lrp13 showed that both receptors were expressed during vitellogenesis with LR8 and Lrp13 expression highest in early- and mid-vitellogenesis, respectively. The VtgAa within the ovary peaked during post-vitellogenesis, while VtgAb peaked during early-vitellogenesis in both white perch and the closely related striped bass (M. saxatilis). The VtgC was steadily accumulated by oocytes beginning during pre-vitellogenesis and continued until post-vitellogenesis and its composition varies widely between striped bass and white perch. In striped bass, the VtgC accounted for 26% of the vitellogenin-derived egg yolk, however in the white perch it comprised only 4%. Striped bass larvae have an extended developmental window and these larvae have yolk stores that may enable them to survive in the absence of food for twice as long as white perch after hatch. Thus, the VtgC may play an integral role in providing nutrients to late stage fish larvae prior to the onset of exogenous feeding and its composition in the egg yolk may relate to different early life histories among this diverse group of animals.     

The influence of hunger on food‐stocking behaviour of climbing perch Anabas testudineus

The present study demonstrated that the climbing perch Anabas testudineus collected and stocked food pellets in its mouth, a behaviour that has not yet been reported in any other species of fish. In this species, food deprivation for 24 h increased food stocking, but not food intake.     

Inferring Processes from Spatial Patterns: The Role of Directional and Non–Directional Forces in Shaping Fish Larvae Distribution in a Freshwater Lake System

Larval dispersal is a crucial factor for fish recruitment. For fishes with relatively small-bodied larvae, drift has the potential to play a more important role than active habitat selection in determining larval dispersal; therefore, we expect small-bodied fish larvae to be poorly associated with habitat characteristics. To test this hypothesis, we used as model yellow perch (Perca flavescens), whose larvae are among the smallest among freshwater temperate fishes. Thus, we analysed the habitat association of yellow perch larvae at multiple spatial scales in a large shallow fluvial lake by explicitly modelling directional (e.g. due to water currents) and non-directional (e.g. due to aggregation) spatial patterns. This allowed us to indirectly assess the relative roles of drift (directional process) and potential habitat choice on larval dispersal. Our results give weak support to the drift hypothesis, whereas yellow perch show a strong habitat association at unexpectedly small sizes, when compared to other systems. We found consistent non-directional patterns in larvae distributions at both broad and medium spatial scales but only few significant directional components. The environmental variables alone (e.g. vegetation) generally explained a significant and biologically relevant fraction of the variation in fish larvae distribution data. These results suggest that (i) drift plays a minor role in this shallow system, (ii) larvae display spatial patterns that only partially covary with environmental variables, and (iii) larvae are associated to specific habitats. By suggesting that habitat association potentially includes an active choice component for yellow perch larvae, our results shed new light on the ecology of freshwater fish larvae and should help in building more realistic recruitment models.     

Influence of diurnal rhythms of feeding during intestine total amylolytic activity and activity of alkaline phosphatase in juvenile fish

The total amylolytic activity and activity of alkaline phosphatase in the intestine mucosa of larvae and fries of roach, blue bream, and perch change both during the process of individual development and during the day. Maximal intensities of juvenile feeding was observed primarily in the morning and evening hours. The pattern of diurnal alkaline phosphatase activity correlates to a greater extent to intensity of juvenile feeding, in comparison to the pattern of total amylolytic activity. In planktivorous blue bream, such regularity is more pronounced than in benthivorous roach. The total amylolytic activity in fries of roach, blue bream and perch correlates to fish type of feeding.     

Effect of Urea and Thiourea on Migration Activity of Climbing Perch Anabas testudineus

Journal of Ichthyology - The influence of urea and thiourea on the dynamics of the migration activity of climbing perch Anabas testudineus was studied. The exposure of climbing perch to 0.05%...     

Development of Thelastoma bulhoesi (Oxyurata: Thelastomatida) and the Effect of Thiabendazole on the Unembryonated Egg

The embryological and postembryological development of Thelastoma bulhoesi was determined. Initial cleavage was into unequal cells and occurred within 1-2 hours at 25 C. Cell division was holoblastic but no true morula is formed. Gastrulation occurred at approximately 48 hours by epibolic synectic mechanisms. First-stage larvae were fully developed at 96 hours. The molt to second-stage larvae was initiated in the egg and was completed at hatching. Second-stage larvae were first observed in the host at 11 hours postinfection, third-stage larvae at 18 hours, and fourth-stage larvae at 192 hours. Adult female worms were observed at 32 days. Thiabendazole, in even the lowest concentrations, inhibited the developmem of unembryonated ova.     

Corytibacladius Oliveira,Messias & Santos, 1995, a junior synonym of Limnophyes Eaton, 1875 (Diptera: Chironomidae: Orthocladiinae)

Larvae of the blackfly Simulium noelleri Friederichs aggregate at high populatio n densities on dams and spillways at the outlet of ponds. When displaced into the water column from their point of attachment, larvae can secrete silk threads as "life-lines" which enable them to maintain a link to the substratum an d up which they can climb to regain their original position. Experiments were conducted in a laboratory pond outlet to investigate this use of silk threads, larvae being displaced by means of forceps. It was demonstrated that: (i) the length of thread produced , and the speed of climbing the thread are independent of larval size; (ii) within limits, the speed of climbing was independent of both the length of the thread and the time already spent climbing, and (iii) speed of climb became more rapid as larvae neared the point of attachment. The range of locomotion in blackfly larvae is then discussed.     

Development of the sand dollar <Emphasis Type="Italic">Scaphechinus mirabilis</Emphasis>

Under laboratory conditions, the development of larvae of the sand dollar Scaphechinus mirabilis (Agassiz) took 28.5–29 days from fertilization to settling and the end of metamorphosis at a temperature 20°C and salinity 32.2–32.6‰ The cleavage divisions were completed in 12 hours after fertilization (AF) by the release of free swimming ciliary blastula from the egg membrane. The larvae attained pluteus I stage with one pair of arms at an age of 40 hours. In 4.5–5 days the pluteus II stage with three pairs of arms, and in 9 days the pluteus III stage with four pairs of arms were formed. On the 20–21st day AF the larvae developed a vestibule, in which the adult skeleton rudiments, spicules, plates and pedicellariae were formed on the 26–27th day AF. The size of the larvae at an age of 22.5 days was 1064.3 ± 44.7 μm. The settling of larvae was recorded on the 28–29th day of development. Most of the larvae completed their metamorphosis in 4.5–5 hours after settling.     

Predation of perch on vendace larvae: diet composition in an oligotrophic lake and digestion time of the larvae

The diet of perch Perca fluviatilis was studied to reveal possible predation on vendace Coregonus albula larvae in an oligotrophic lake. Perch diet changed with the size of the fish: small perch ate mainly zooplankton and the diet shifted more to benthic invertebrates and fishes in larger perch. There were also annual and spatial differences in the diet, probably reflecting differences in the availability of prey animals. Perch predation on vendace larvae was only observed in the area with high availability of the larvae. The result suggested strengthened predation when the density of the larvae increases. According to bioenergetics modelling, the perch population increased natural mortality of vendace larvae only marginally. Food intake of spawning female perch was slightly reduced, whereas spawning males fed similarly to non-spawning males. Hence, the spawning period of perch was only a minor refuge for vendace larvae. Laboratory experiments of perch digestion rate demonstrated that, due to rapid digestion of the small fish larvae, diet sampling interval should not be >2 h in the field.