Histopathology of the Liver of Three-Spotted Gourami, Trichogaster Trichopterus, Exposed to Malachite Green, A Commonly Used Medicine in Aquaria

With the intensification of aquaculture and the heightened interest in ornamental fishes and fish keeping, use of medicaments has considerably increased. These agents are heavily bio accumulated by fish. In spite of this importance of drugs/therapeutic agents in fishery science, no serious attempt has been made to assess their effects on fishes, especially the histopathological changes brought about by them. Liver is the chief metabolic and detoxification organ in vertebrates and it is highly susceptible to metabolic disturbances and a variety of toxicants to which the animal is exposed. Results of controlled exposure of fishes in the laboratory to toxicants such as pesticides and related chemicals suggest that liver is the organ in which the highest residues of such toxicants accumulate and it is this organ that suffers the greatest damage and impairments following such episodes. The present study was, therefore, aimed at assessing the histopathological effects of therapeutic level of malachite green on the liver of a common aquarium fish, the three spotted (blue) gourami, Trichogaster trichopterus. The drug selected for the present study was malachite green, a chemical recommended for treatment of fishes against several infection, especially fungal infection of eggs. Malachite green is used at concentrations of 0.05-0.15 ppm in fish disease therapy. Healthy fishes of about 70.0±5 mm TL purchased from a local aquarist were used for the present study. Fish were exposed to malachite green for a period of 48 h in all-glass aquarium tanks. The exposure concentration of malachite green was 0.15 ppm. The procedures for histological studies were basically in accordance with the commonly practiced histological methods.

Growth, feed conversion and retention, and proximate of eel juvenile treated by immersion of recombinant giant grouper growth hormone

<p>This study was aimed to determine the immersion dose of recombinant giant grouper growth hormone (rElGH) to increase growth of eel juvenile (glass eel). After shock salinity treatment (NaCl 3% for 2 min), glass eel were immersed in water containing 0.9% NaCl, 0.01% bovine serum albumin, and different of dose of rElGH (0, 0.12, 1.2, 12 and 120 mg/L). Glass eel were fed on blood worm for the first month, and commercial diet for the second month of rearing. Fish rearing was performed in 60 L glass aquarium at density of 150 fish per aquarium. The results showed that higher in growth body weight was obtained in immersion dose of 12 mg/L, by increment of about 37.4% higher compared to that of control. The immersion dose of 12 mg/L also increased specific growth rate by 29.3% higher (p&lt;0.05) compared to control. Furthermore, at that immersion treatment, feed conversion ratio of blood worm and commercial diet decreased by 33.7% and 25.6% compared to control, respectively. Protein (7.15±0.08%) and lipid (9.95±0.10%) retentions in 12 mg/L rElGH-treated fish were higher (p&lt;0.05) than those of control (protein 6.17±0.07%; lipid 5.73±0.06%). Lower in protein content (12.73%), while higher content in lipid (8.35%) and crude carbohydrate (3.22%) were found in 12 mg/L rElGH-treated fish compared to those of control (13.24%, 5.90%, and 1.76%, respectively). Thus, in general, rElGH immersion dose of 12 mg/L could generate high performances of eel juvenile, and application of rElGH can be useful to increase aquaculture eel production.</p><p>Keywords: immersion dose, growth hormone, growth, glass eel</p>

Heterogeneous growth fingerlings of the Nile tilapia Oreochromis niloticus: effects of density and initial size variability

In this study, the effect of initial heterogeneity of weight and density on heterogeneous growth (HetG) evaluated by the coefficient of the variation of weight in the young Nile tilapia Oreochromis niloticus of the territorial species was tested. Fish were maintained in a glass aquarium (8 and 2 L of water) with two levels of initial heterogeneity of weight: low and high, under two density conditions: low and high, thus constituting four conditions (six replications for each). Initially, the weights of the animals were taken after 8, 16, 22 and 30 days (end of experiment). The results, evaluated by the non-parametric test of Kruskal- Wallis, demonstrated that in the groups where the animals were stored under high initial HetG, there was a reduction of the same and that in the groups where the animals were stored under high density, there was exacerbation or maintained high values of HetG. High density in association with high initial heterogeneity caused more exacerbation of HetG in such a way that the density appeared to be a determining factor for exacerbation or the maintenance of high values of HetG, whereas the initial heterogeneity of the weight could be a secondary factor.

Food patch depletion by ruddy ducks: foraging by expectation rules

The foraging behavior of six ruddy ducks (Oxyura jamaicensis) was studied in a large concrete and glass aquarium to determine if they used either a number or time expectation rule to decide when to leave a patch of food. Nine trials were conducted in which the prey density in each of two food patches remained constant for three consecutive trials and then was changed. If the foraging ruddy ducks were using an expectation rule to determine when to leave a patch, then the time spent in the patch (time expectation) or number of prey consumed from the patch (number expectation) should not change with a change in patch quality. The results of this experiment were not consistent with the predictions of either the time or number expectation rule. Thus, ruddy ducks appear to use some other measure to determine the appropriate time to leave a food patch.

Comparison of growth performance between cryopreserved and fresh sperm-originated fry of Barbonymus gonionotus

This experiment was conducted to compare the growth performance of silver barb fry produced from cryopreserved sperm with those produced from fresh sperm. Cryopreserved sperm used for fry production was preserved with three extenders, Alsever's solution, urea egg-yolk, egg-yolk citrate solution and one cryoprotectant, DMSO. Cryodiluents were prepared by mixing the cryoprotectants at 10% concentration of the extender (% v/v). Fry produced with fresh sperm was considered as control. For comparing the growth, 60 fry of 15 day-old for each treatment of both cryopreserved and control groups were stocked to glass aquarium (50 cm x 30 cm x 28 cm) and reared them for ten weeks. Growth of fry in terms of length and weight increment in both cryopreserved and control groups were measured weekly. The growth pattern was more or less similar for all the treatments and there was no significant difference (P>0.05) between them. The survival rate of fry produced from cryopreserved sperm was 82.3% and that from fresh sperm 88%, and there was no significant difference (P>0.05) between two groups. It is therefore, concluded that the use of cryopreserved sperm does not impair survival and growth of fry. Keywords: Silver barb; Cryopreservation; Growth; Survival DOI: 10.3329/jbau.v7i1.4977 J. Bangladesh Agril. Univ. 7(1): 145-149, 2009

A Contribution towards the Life History of Parorchis acanthus Nicoll, A Trematode in the Herring Gull

Parorchis acanthus is a Trematode described by Nicoll (1907) from the bursa Fabricii and rectum of the Herring Gull, Larus argentatus; in 1906 he first described it as Zeugorchis acanthus. Originally found at St. Andrews, it is now known to be common at Millport and also occurs in gulls from the Northumberland coast, and probably is abundant elsewhere. Nicoll found it once in the Common Gull, Larus canus. In 1907 (Lebour, 1907) one of the present writers described a cercaria occurring in rediæ from Purpura lapillus. This was named Cercaria purpurœ sp. inq., and afterwards identified with young stages of Parorchis acanthus in the Herring Gull (Lebour, 1914). It was thus shown that the first host of this Trematode is Purpura lapillus and the final host the Herring Gull, but the intermediate host was unknown. Localities for the cercaria were Loch Ryan, Wigtownshire; Budle Bay, Fenham Flats and Cullercoats in Northumberland; Robin Hood's Bay in Yorkshire; and Millport. Adults occur at St. Andrews, Northumberland coast and Millport, as already stated.The Cercaria appeared to be closely related to Echinostomum cercariæ, and it was suggested (Lebour, 1914) that the intermediate host would probably be some marine bivalve, as it is often so with Echinostomum (e.g. E. secundum in Mytilus edulis and Cardium edule, E. leptosomum in Scrobicularia tenuis). This suggestion now proves to be correct, and we are able to show that the intermediate host of Parorchis acanthus is Mytilus edulis or Cardium edule.On August 13th, 1921, at the Millport Station some larval cercariæ were noticed by Elmhirst swimming in a small glass aquarium, which contained a collection of Purpura lapillus, Cardium edule and Mytilus edulis.

Note on a Leptocephalus Stage of the Conger

On September 17th, 1919, a specimen of Leptocephalus Congri vulgaris (L. Morrisii) was captured in “bottom” haul No. 69 of the young fish trawl in locality Eddystone bearing S. by W. (magnetic) 1½ miles, over a depth of 31 fathoms. It was alive and active when taken, measuring between 115 and 120 mm. in length, and has been kept alive up to the present date in a glass aquarium under circulation. It was at a fairly advanced stage of development, intermediate between those exhibited in Figs. 2 and 3, Pl. I of Schmidt (1), the dorsal fin commencing slightly farther back than in Fig. 3, and the median row of pigment spots along either side of the body not extending forward beyond about 1 cm. in front of the commencement of the dorsal fin. There is a close resemblance also to the specimen figured by Fulton (2), with the exception that, as just pointed out, the median row of pigment along the body on either side does not reach forward quite to the head, and in addition the pigment spots at the base of the dorsal fin rays are only two or three in number, situated at the extreme posterior end of the fin.Since the date of capture, observations 'have been made periodically and certain measurements taken as accurately as possible, but on account of the movements of the fish the latter could only be obtained approximately.