Effect of Color During Transport and Anesthetic Efficacy of Alcoholic Drink, 2-Phenoxyethanol, Clove Oil, MS-222, and Benzocaine in Silver Therapon, Leiopotherapon Plumbeus (Kner 1864)

The study evaluated the survivability of silver therapon, Leiopotherapon plumbeus (Kner, 1864) in different color containers during transport and the efficacy of five anesthetic agents [alcoholic drink, 2-phenoxyethanol, clove oil, tricaine methanesulfonate (MS-222), and benzocaine] in the induction and recovery time of L. plumbeus. Different colored polyethylene bags (black, red, yellow, blue, and transparent) did not influence the survival rate of fish until the termination of the experiment (12-h transport time). The immersion experiment used three different concentrations in each anesthetic agent with three replicates (ten fish specimens per replicate). Different dosages significantly influenced the induction time, with decreased induction efficacies in high dosages. Moreover, the 200 ml L-1 and 300 ml L-1 alcoholic drinks anesthetized the fish specimens comparable to the induction efficacy of several dosages of 2-phenoxyethanol, MS-222, and benzocaine. Recovery time significantly varied among treatments, with a prolonged recovery period with increasing anesthetic concentrations. Regression analysis revealed a positive correlation between fish standard length and induction time (P < 0.05), albeit more pronounced in smaller dosages. Induction and recovery times were not correlated to fish size when exposed to higher dosages. The present finding demonstrated the anesthetic efficacy of four commercial anesthetic solutions, so as with alcoholic drinks with concentrations between or equal to 200 ml L-1 and 300 ml L-1. Experimental trials for fish euthanization and field trials are open for further investigation

Growth and survival of nile tilapia (Oreochromis niloticus) juveniles fed diets with varying levels of irradiated chitosan

Abstract only.Chitin is a natural biopolymer and the second most abundant after cellulose. Chitosan, a derivative of chitin which is soluble in acidic aqueous media, is used in many applications like food, cosmetics, biomedical and pharmaceutical products. It is used in agriculture for enhancing growth in crops while in aquaculture, chitosan is believed to improve the immune response of fish to stress-inducing agents, thus enhancing survival and possibly growth. This preliminary study was conducted to investigate the effects of various concentrations of irradiated chitosan on the growth performance of Nile tilapia, O. niloticus. Fish was fed with a control diet and three formulated diets containing increasing levels of irradiated chitosan (10g, 20g and 50g kg-1). Juvenile O. niloticus was fed once daily for 21 days. The ration was based on 5% of the fish biomass. Tilapia fingerlings (n=30 per tank) of uniform size were randomly distributed in four experimental groups each with three replicates following a completely randomized design. Growth and food utilization parameters were measured. Specific growth rate (SGR), mean weight gain (MWG), mean length increment (MLI) and feed conversion ratio (FCR) were computed and analyzed using ANCOVA. Results from the feeding trials showed no significant difference (P>0.05) in the different performance parameters under the different fish feed treatments. MWG, MLG, SGR and FCR varied in the stocks fed different fish feed treatments but with no significant differences. The results also showed 45-62% survival ratio. These suggest that although there is no significant difference between treatments and control, irradiated chitosan-supplemented diets do not retard the growth of O. niloticus. Chitosan should be studied further to determine how it can improve the growth performance, feed utilization and immune response of Nile tilapia

Larval rearing of silver therapon (Leiopotherapon plumbeus) in outdoor tanks

Abstract only.Silver therapon (Leiopotherapon plumbeus, Kner 1864), locally known as ayungin, is an important freshwater food fish species found in Laguna de Bay, the largest lake in the Philippines. Its market price is twice that of other most sought after freshwater fishes such as tilapia and milkfish. However, intense fishing pressure on the species has significantly reduced the wild stock in Laguna de Bay. Studies to develop hatchery techniques for this indigenous freshwater fish species are therefore needed to produce seedstock for possible culture and wild stock rehabilitation. This study highlights the successful larval rearing of silver therapon in outdoor concrete tanks. Larvae reared in outdoor tanks with natural food (grown two weeks beforehand) reached the juvenile stage (40 days after hatching (DAH)), suggesting the presence of some suitable live food organisms in pre-conditioned rearing water. However, larval survival rates were low (11.58 ± 6.56% at stocking density of 0.9 larvae l-1), which is probably linked to the density of food items, particularly during the onset of exogenous feeding or due to high stocking density of larvae. To improve the availability of natural food for the larvae, fertilization of the rearing water in the outdoor tanks stocked with larvae at two densities (0.4 and 0.6 larvae l-1) was performed. Larval growth and survival were improved at stocking density of 0.4 larvae l-1 than at 0.6 larvae l-1. Diet composition of first-feeding silver therapon larvae in outdoor tanks inoculated with cultured microalgae (Chorella sorokiniana) and zooplankton was also determined. Larvae were able to consume rotifers and some phytoplankton beginning at 2 DAH and larger preys such as cladocerans and insect larvae starting at 12 DAH. The efficacy of raising silver therapon larvae in outdoor tanks using ambient lake water was also evaluated. Larvae reared in ambient lake water grew well but survival (48.44 ± 7.85%) was significantly improved in treatments where tropical almond or talisay Terminalia catappa leaves were added during the first two weeks of larval rearing

Optimization of feeding and growth conditions for hatchery-bred larvae of indigenous Philippine silver perch, Leiopotherapon plumbeus (Perciformes: Terapontidae)

Abstract only.The Philippine silver perch, locally known as ayungin, is an endemic fish species and is considered as a potential candidate for aquaculture and for stock enhancement. However, high mortality associated with early larval stages presents a significant bottleneck to its latent commercialization. Culture experiments considered interactions among prey proportions, growth conditions and their consequences on fish growth performance and survival. Two phases of the experiment were conducted: (1) a short duration feeding trial utilizing different prey proportions of Brachionus calyciflorus and Moina macrocopa and (2) an indoor larval rearing technique that ensured optimum growth and survival of juveniles. Findings of this research will be used to propose an efficient rearing strategy addressing the aquaculture of this indigenous species

Effect of Adding Different Levels of Duckweed (Lemna minor Linn.) in the Diet on Live Body Weight, Hematological Traits and Production Cost of Free-range Chickens, Gallus domesticus Linn. (Black Austrolorp x Barred Playmouth Rock)

The present study was conducted at Bataan Peninsula State University Abucay Campus to evaluate the growth performance and hematological profile of Gallus domesticus Linn. (Black Austrolorp x Barred Playmouth Rock) chicken fed formulated diets of varying inclusions of lesser duckweed (Lemna minor Linn.). Three formulated treatments diets of homogenous crude protein level were prepared: 0% duckweed (control), 10% duckweed, and 15% duckweed inclusion. Five chickens (average weight 202.5 g) per replicate were reared in a single factorial experiment and the feeding trial was carried-out for three months. Chicken fed diet containing 15% duckweed meal treatment had significantly (P < 0.05) higher body weight (1,425.88 ± 55.24 g) compared to chicken fed normal diet (1,223.48 ± 174.47 g). Mean cost to produce a kilogram of meat was significantly cheaper in the treated diets (F = 4.82; P < 0.05). Mean values of hematological variables were not significantly different among treatments

Sexual Dimorphism, Growth Rate, and Condition Factor Dynamics in Glossogobius celebius (Perciformes: Gobiidae)

There is a paucity of information concerning diminutive gobies in the Philippines. Sexual dimorphism in Celebes goby Glossogobius celebius (Valenciennes, 1837) was described based on the external morphology of the specimens from Orani river systems, Bataan, Philippines. The mean body size of females was larger than males but not significantly different (p > 0.05). The principal component analysis identified the longer snout-to-2nd dorsal fin length, snout-to-anal fin length, and deeper body of females, while males have longer median fins (anal fin and 2nd dorsal fin). Multivariate analysis of variance examined significant variation among and between the sex and maturity groups (Pillai trace = 1.52, F = 13.98, p < 0.001). In canonical variate analysis, a significant morphological deviation between immature and mature specimens is primarily explained by more posteriorlylocated anal fin and 2nd dorsal fin, and longer 2nd dorsal fin by the latter. Moreover, the difference between sexes of mature specimens was evident in males having a more elongated 2nd dorsal fin. The observed variation can be attributed to developmental priorities (maturation-related morphology) and the health status of the specimens. Both sexes displayed statistically isometric growth rate (male b = 2.99; female b = 3.03). The relative condition factor (K) was closed to a K-value of 1.00, indicating a state of well-being for the collected fish specimens

Morphometric and morphomeristic variations in five populations of indigenous Celebes goby Glossogobius celebius (Perciformes: Gobiidae) from Southern Luzon, Philippines

To elucidate the population structure and pattern of morphological divergence of the indigenous Celebes goby Glossogobius celebius (Valenciennes, 1837), morphometric and morphomeristic characters of this species were compared among populations collected from five study sites in Southern Luzon, Philippines. Univariate analysis of variance confirmed significant differences among populations for 20 out of 23 allometrically-transformed metric characters (P0.05). Intrapopulation variability was very low (6.81-7.21%) for each location. Multivariate analysis of variance determined a very high significant group variability (P<0.05). Also, principal component analysis (PC1=36.60%; PC2=18.34%) and canonical variate analysis (CV1=44.59%; CV2=37.30%) identified the 2 super(nd) dorsal fin length, anal fin length, and the 2 super(nd) dorsal fin origin as the main significant contributors of population differentiation. Derived classification functions correctly classified an average of 68% individuals into their original groups. The canonical variate analysis plot exhibited high isolation of lacustrine populations (Lake Taal and Laguna de Bay) from riverine populations (Dampalit River, Alitaaw River and Pansipit River), with the latter having longer metric characters. Likewise, squared Euclidean distance similarity using metric data clearly produced two clusters representing both river and lake populations. This morphological divergence is suggested to be environmentally-induced (phenotypic plasticity) primarily by the differences in flow rate and temperature of the study sites

Larval and early juvenile development of silver therapon, Leiopotherapon plumbeus (Actinopterygii: Perciformes: Terapontidae), reared in mesocosms

The silver therapon, Leiopotherapon plumbeus (Kner, 1864), is an endemic and economically important freshwater food fish in the Philippines. The natural populations of this species have been declining during the past years, mainly due to intense fishing pressure, habitat degradation, and introduction of invasive alien species. At present, it is considered a target species for domestication and conservation efforts. Despite several attempts of artificial reproduction and larval rearing, little is known on larval and early juvenile development of silver therapon. The presently reported study was therefore intended to fill this gap in the knowledge by determining the growth and describing body proportions, pigmentation, and fin formation of this fish. Newly hatched larvae were reared in mesocosm tanks at a mean temperature of 29.5°C. Larvae up to 30 days after hatching were sampled at irregular intervals and preserved in 5% buffered formalin. Early development stages for 245 preserved specimens were described in detail with reference to changes in morphology, growth and body proportions, pigmentation, and fin formation. Five developmental stages of silver therapon were identified: yolk sac larva (1.88 mm TL), preflexion (2.51 mm TL), notochord flexion (4.50-8.27 mm TL), postflexion larva (6.90-12.21 mm TL), and early juvenile (>13.40 mm TL). Growth was isometric for eye diameter and gape size whereas positive allometry was observed for body depth, head length, and preanal length. Some body proportions showed abrupt changes from preflexion to postflexion larvae before it stabilized during the early juvenile stage. Pigmentation in the form of stellate and punctate melanophores increased with developmental stage, with larvae becoming heavily pigmented from postflexion to early juvenile stage. These morphological changes, together with the full complement of fin rays and squamation observed in specimens larger than 13.4 mm TL, suggest the attainment of the juvenile stage of this species. These morphological changes may explain the food and feeding habits during the early life stages of silver therapon which is critical to their survival and recruitment in the wild and in a mesocosm hatchery environment.This work was supported by SEAFDEC Aquaculture Department under the Study code: Nr-04- F2010B. We express our gratitude to Miss Julie Andrea P. Añano, Mr Nemencio B. Olorvida and the student interns from the Polytechnic University of the Philippines (Santa Mesa, Manila) for their assistance during the study

Diversity and distribution of freshwater fish assemblages in Tayabas River, Quezon (Philippines)

Three stream sections (upstream, midstream, and downstream) of Tayabas River, Philippines were surveyed during the wet and dry seasons of 2010 to evaluate the poorly known status of freshwater fish assemblages. The study collected a total of 1,070 individuals comprising 15 species, 13 genera, and 8 families. The three most abundant groups were poeciliids (61.85%), gobiids (26.16%), and cichlid (5.51%). Shannon-Weiner’s diversity indices ranged from 1.270 to 2.171. Relatively high Shannon evenness indices (0.653–0.846) and low Simpson’s dominance values (0.142–0.322) were calculated implying a fairly equitable distribution of niche space for dominant and non-dominant fishes. Significant change on fish assemblage in longitudinal gradient was observed (p&lt;0.05), being the most diverse fish assemblage registered in the upstream. Species richness is mostly composed of native fish species (10 species) and mainly represented by stream gobiids (six species). The downstream, however, had the highest cumulative abundance, in which the larger proportion was from introduced species. Also, wet season had considerably more fish species and individuals relative to dry season (p&lt;0.05). This significant spatio-temporal differences in fish assemblage data were evaluated by multivariate analyses (p&lt;0.05). Canonical correspondence analysis identified the depth (seasonal water level fluctuations), vegetation growth, and dissolved oxygen concentrations (in order of importance) as the most influential environmental parameters affecting fish assemblage structure. Also, climatic stress (prolonged drought) and anthropogenically-induced habitat alteration could negatively affect the integrity of freshwater fishes within the river. The study suggests extensive management programs of the river for the protection of native fish species