​Discrimination of Five Gobid Species (Family: Gobiidae) based on Otolith Morphometry

Background: The fishes of family Gobiidae are one of the least studied fishes, especially for otolith structure. The otoliths were possess species specific features. Hence, traits of sagittal otolith of gobid species studied. Methods: Five gobid species Odontamblyopus roseus (Valenciennes, 1837), Trypauchen vagina (Bloch and Schneider, 1801), Glossogobius giuris (Hamilton, 1822), Parachaeturichthys polynema (Bleeker, 1853) and Boleophthalmus dussumieri (Valenciennes, 1837) were investigated by three methods including morphological, shape indices and step wise discriminant function analysis (SDFA). Result: Interrelationship between shape indices investigated, at 95% level of confidence (P less than 0.05), revealed that perimeter of P. polynema and area of T. vagina have isometric growth with their length (b = 3.0071, 2.90, respectively) and otolith area of B. dussumieri have positive allometric growth (b = 4.23077). SDFA, based on otolith morphometry, discriminated species up with 97.18% accuracy. Hence, the results of present investigation can be used for discrimination of the species and as a tool in predicting fish size from the otoliths and in calculating the biomass of these less studied fish species.

Hepatic Microsporidiosis of Mudskipper, Boleophthalmus Dussumieri Valenciennes, 1837 (Perciformes: Gobiidae), Due to Microgemma Sp.

The present study reports a case of hepatic microsporidiosis caused by Microgemma sp in brackishwater fish, Boleophthalmus dussumieri (Valenciennes, 1837) (n = 60), from north-west coast of India. An eight-month study from September 2017 to April 2018 revealed a prevalence of 11.6% for this parasite. The microsporidian showed tissue-specific infection and did not reveal any gross pathology in infected fish. Large whitish cysts containing microspores of size 0.3–0.5 mm were observed in the liver of fish. The range of pyriform microsporidian spore size varied from 2.9–3.77 X 1.85–2.67 µm. Histological observations of infected liver revealed large xenoma of the microsporidian filled with spores and encircled by a cyst wall-like layer. Scanning electron microscopy of the spores showed a distinct groove on the anterior end of the spore for polar tube extrusion. Polymerase chain reaction (PCR) amplification of the DNA extracted from the microsporidian spores using primers targeting small ribosomal subunit DNA (SSU rDNA) yielded ~ 1340 bp amplicon and the genetic distance analysis showed a 0.2% variation with the reported M. tilanpasiri. Accordingly, in the phylogenetic tree, the present species of Microgemma clustered with M. tilanpasiri. Even though, the morphomeristic characters of the present Microgemma sp. was marginally different from the reported M. tilanpsasiri; the SSU rDNA showed considerably higher similarity with M. tilanpasiri. Thus, we report the species of Microgemma as Microgemma aff. tilanpasiri from a new host. This is the first report of a microsporidian from B. dussumieri and the first record of the genus Microgemma from India.

Identification and the First Record of Marine bacteria Mudskippers Boleophthalmus dussumieri (Valenciennes, 1837) by 16S rRNA on the Northern Intertidal areas of Persian Gulf, Iran

Background Mudskipper is from the Gobiidae family and from the subfamily Oxudercinae. Mudskipper contains four main genera Boleophthalmus, Periophthalmodon, Periophthalmus, and Scartelaos. The aim of this research identification of bacterial agent (Marine bacteria) mudskippers Boleophthalmus dussumieri on the Shores of the northern intertidal areas of the Persian Gulf (Abadan, Hendijan and Bahrekan), Iran. The mud sediment and water samples (at the depth of one m), and mudskipper fish samples (near shore at the intertidal) were collected from Abadan, Hendijan and Bahrekan in northern coasts of the Persian Gulf, Iran. Results A total of 80 aerobic bacteria marine (from the intestines of mudskipper, seawater, and muddy sediments ) was identified by biochemical tests and 16S rRNA gene sequence analysis. The bacteria's (Marine bacteria) [Eubacterium] tenue strain DSM 20695, Praclostridium bifermentans strain JCM 1386 and Vibrio hyugaensis strain 090810a was first identified in the northern intertidal areas of Persian Gulf, Iran. Conclusions Bacteria compete with other organisms to get oxygen to the surface layers of the flower bed. They give that the bacterial species common to the fish intestines and sediments is high and due to fish feeding of sediment it can be concluded that the species present in the fish intestine in the present study may be a function of substrate species that needs further studies to prove this.