The effects of LED light spectrum manipulation on growth and color performance of giant gourami Osphronemus gouramy Lacepede Padang strain

This study aimed to evaluate the effect of light spectrum on growth and color performance of giant giant gourami Padang strain. The experiment used a completely randomized design (RAL) with four light emitting diode (LED) treatments in different emission spectra (white, red, green, and blue) at 550 Lux intensity, compared to the control treatment (light room with white tubular lamp at 50 Lux intensity). The irradiation was carried out for 12 hours of photoperiod. The fish used had the total length of 82.90±4.2 mm and body weight of 9.87 ± 0.99 g. The highest growth performance was found in blue LED treatment with the specific growth rate of 2.73 ± 0.2% and feed efficiency of 86.26 ± 2.71%. The best color performance was found in red LED treatment with the RGB ratio of 44.57 ± 0.62% in dorsal fin, 38.41 ± 1.36% in pectoral fins, and 45.33 ± 2.25% in anal fin with the chromatophore cell concentration at 1.973±58 cells/mm2. Keywords : Osphronemus gouramy, blue LED, spectrum, chromatophore, light ABSTRAK Penelitian ini bertujuan untuk mengevaluasi pengaruh spektrum cahaya terhadap kinerja pertumbuhan dan warna ikan gurami strain Padang. Rancangan penelitian yang digunakan adalah rancangan acak lengkap (RAL) dengan 4 perlakuan cahaya lampu light emitting diodes (LED) yang memiliki spektrum panjang gelombang berbeda (putih, merah, hijau dan biru) intensitas 550 Lux dan kontrol (cahaya ruang berasal dari lampu tubular putih intensitas 50 Lux). Penyinaran dilakukan selama 12 jam mengikuti fotoperiod. Ikan uji yang digunakan memiliki panjang total 82,90 ± 4,2 mm, dengan bobot 9,87 ± 0,99 g. Kinerja pertumbuhan terbaik terdapat pada perlakuan LED biru dengan laju pertumbuhan spesifik sebesar 2,73 ± 0,2% dan efisiensi pakan sebesar 86,26 ± 2,71%. Performa warna terbaik terdapat pada perlakuan LED merah dengan rasio warna merah pada RGB bagian dorsal sebesar 44,57 ± 0,62%, sirip pektoral sebesar 38,41 ± 1,36%, dan sirip anal sebesar 45,33 ± 2,25% dengan jumlah sel kromatofor sebanyak 1973 sel/mm2. Kata kunci : Osphronemus gouramy, LED biru, spektrum, kromatofor, cahaya

Design of a Labriform-Steering Underwater Robot Using a Multiphysics Simulation Environment

Bio-inspired solutions devised for Autonomous Underwater Robots are currently investigated by researchers as a source of propulsive improvement. To address this ambitious objective, the authors have designed a carangiform swimming robot, which represents a compromise in terms of efficiency and maximum velocity. The requirements of stabilizing a course and performing turns were not met in their previous works. Therefore, the aim of this paper is to improve the vehicle maneuvering capabilities by means of a novel transmission system capable of transforming the constant angular velocity of a single rotary actuator into the pitching–yawing rotation of fish pectoral fins. Here, the biomimetic thrusters exploit the drag-based momentum transfer mechanism of labriform swimmers to generate the necessary steering torque. Aside from inertia and encumbrance reduction, the main improvement of this solution is the inherent synchronization of the system granted by the mechanism’s kinematics. The system was sized by using the experimental results collected by biologists and then integrated in a multiphysics simulation environment to predict the resulting maneuvering performance.

Compartment Syndrome and Wrist Disarticulation After a Catfish Sting

Catfish have the ability to inflict stings on their victims through spines located on their dorsal and pectoral fins. The stings of catfish can release toxins that have dermonecrotic, edemogenic, and vasospastic factors. In this case, a 56-year-old man suffered a catfish sting to his right thumb, which resulted in acute hand compartment syndrome and resultant hand fasciotomies. His hospital course was complicated by multiple irrigation and debridements, finger amputations, hand fluid cultures positive for Vibrio damsela, and eventual wrist disarticulation. The combination of envenomation, infection, and delayed presentation for treatment ultimately led to a hand amputation.

Behavioral and Biophysical Studies of Dugong (Dugong dugon) Habitat in Waters Mali Beach, Kabola District, Indonesia.

Dugongs are generally shy animals, so observing their existence is very limited to hundreds of meters. In contrast to the behavior of Dugong who lives in the coastal waters of Mali, Kabola Regency, Indonesia. Its uniqueness can interact with humans at a very close distance and can even be on the back. It is, therefore, necessary to explore other behavioral patterns and habits and biophysical habitats of Dugongs as information to maintain their survival. This research aims to find out the behavior and biophysics of dugong habitat in the coastal waters of Mali, Kabola Subdistrict, Indonesia. The study uses direct observation methods in the form of observing the characteristics and biophysical conditions of dugong habitats including (1) determining dugong activity areas using GPS coordinates; (2) observe habitat characteristics and biophysical conditions by observing biotic and abiotic conditions, and (3) measuring physicochemical parameters, namely temperature, salinity, and pH. Next, to observe the daily behavior of dugongs when interacting with their habitat environment in the form of time: breathing, going around the boat, swimming at the bottom, swimming on the surface, swimming in the water column, resting at the bottom, eating and exposing the back. In the observations, dugongs swimming around the ship immediately responded and then approached and rubbed his body to the leg then through the pectoral fins that tried to hug to get a leg on the model being tested. Then turn under the boat and remove the penis. In general, the biophysical conditions of sandy and dense habitats are overgrown with seagrass.

Interspecific and intraspecific differences in pectoral-fins spine morphology in Nile River and Lake Nasser catfishes, Siluriformes

The structure of the pectoral fins spine of 4 catfish species Heterobranchus longifilis, Clarias gariepinus, Chrysichthys auratus, Synodontis schall and Synodontis serratus were described. The fish specimens were collected from Asyut City and Lake Nasser about 319 and 900 Km south of the capital Cairo, Egypt respectively on 10 November 2017 are described. The species examined showed variation in the shape of the spine-shaft tip varies from finely to broadly and rounded pointed; the curvature of the spine-shaft is either straight or curved partially or complete; the anterior serrae varies between is either broad or irregular; the anterior ridge groove is well developed, deep, and curved, with some pores in some species; the anterior dentations varies between short and sometimes are merged together or curved and their number decreased towards the tip; the posterior dentations can vary between absent or long and numerous and sometimes increased in their number towards the tip of the spine; the dorsal, anterior and ventral processes are well developed structures, with rounded, flange-like, and the shape of the basal fossa varies in having narrow, elongated, boat-shape, with high walls at sides; and very wide fossa and lunate in shape. It is usually deep with high walls.

Huffmanela sp. (Nematoda: Trichosomoididae: Huffmanelinae) encountered in the whitecheek shark (Carcharhinus dussumieri) in the Arabian Gulf

Summary Veterinary inspection of fish caught at the western side of the Arabian Gulf off the shore of Saudi Arabia in 2017 revealed abnormal irregular zigzag black lines in the skins of 135 out of 1500 (prevalence = 9 %) whitecheek sharks (Carcharhinus dussumieri). These lesions have been noticed in the dorsal and ventral part of the head near the snout and around the eyes, as well as in the skin of the pectoral fins. The parasitological, pathological and ultramorphological aspects of the sampled fish were studied using a light microscope, as well as scanning and transmission electron microscopes. Trichosomoidid-type eggs identified as Huffmanela sp. were found in the superficial layer of the skin. The mature eggs containing larvae (n = 75) were ellipsoidal or spindle-shaped, smooth-shelled, amber-brown to dark brown or even black in colour. The width of the eggs ranged from 34 to 49μm with lengths ranging from 95 to 107μm. The polar plugs of the immature eggs were slightly protruding, whereas mature eggs had clearly protruding polar plugs. The width of the polar plugs ranged from 4.5 – 9.5μm. The shells of the eggs were smooth and there was a thin layer seen near the polar areas. The infected skin exhibited desquamated epithelium, with inflammatory cell aggregations and melanophores in the debris. The underlying musculatures of the skin were free from any eggs, but showed mild pathological changes, including congestion of blood vessels, haemorrhages and oedema. The prevalence of infection showed seasonality, peaking significantly in the spring (18.18 %), with comparable prevalence rates in winter and summer (9.43 % and 8.57 %, respectively). However, infections dropped significantly during the autumn months (3.75 %). It is believed that this is the first study reporting the presence of Huffmanela sp. in whitecheek sharks at El-Jubail Province, Saudi Arabia, Arabian Gulf.

No evidence for conspecific recruitment for cooperative hunting in lionfish Pterois miles

Lionfish are common piscivores in the Indo-Pacific and invasive in the Caribbean. A fin flaring pattern, involving a rapid undulation of the caudal fin and sequential turning of both pectoral fins, was described in zebra lionfish as a signal to initiate cooperative hunting, and it was hypothesized that such hunting tactics may also exist in other lionfish species and contribute to their successful invasion in the Caribbean. Here, we investigated one of those invasive species, Pterois miles , in its natural range in the Red Sea. We did not observe evidence for cooperative hunting in the field. We complemented field observations with a laboratory experiment aimed at inducing subjects to recruit partners for cooperative hunts, exposing subjects to inaccessible prey in transparent housing as well as to a potential partner. We regularly observed the fin flaring pattern, but importantly, it was not directed at the partner. Thus, rather than being a signal, the fin flaring movement pattern seems to be a swimming mode in a confined environment. Furthermore, the two lionfish did not aggregate at the prey housing, reinforcing the field results that this species in the Red Sea does not depend on cooperation to hunt fish.

A Numerical Model for the Analysis of the Locomotion of a Cownose Ray

Among all aquatic species, mantas and rays swim by flapping their pectoral fins; this motion is similar to other fishes in terms of efficiency, but it gives better maneuverability and agility in turning. The fin motion is featured by a traveling wave going opposite to the forward motion, producing a force thanks to momentum conservation. This article aims at understanding the swimming dynamics of rays, focusing on energy efficiency. A CFD model of the swimming motion of a cownose ray has been implemented in OpenFOAM, simulating the acceleration of the fish from still to the steady-state velocity using an overset mesh. In this analysis, the 1-DOF dynamics of forward swimming is solved together with the fluid velocity and pressure. The effect of frequency and wavelength of fin motion on thrust, power, and velocity has been investigated and an analysis of the vortices in the wake showed has been performed. The energy efficiency of a self-propelled body has been defined in a novel way and it has been calculated for different motion conditions. The results showed that batoid fishes swim with high energy efficiency and that they are a promising source of inspiration for biomimetic autonomous underwater vehicles.