THE OCEAN DEEP

The electric eel or temblador (Electrophorus electricus), is an electrical fish, and the only species of the genus Electrophorus. It is capable of generating powerful electric shocks, which it uses for both hunting and self-defense. It is an apex predator in its South American range. Despite its name it is not an eel but rather a knifefish.
Anatomy
Electric eels have an elongated, cylindrical body, typically growing to about 2 m (about 6 feet) in length, and 20 kg (about 44 pounds) in weight, making them the largest species of the Gymnotiformes. The coloration is dark gray-brown on the back and yellow or orange on the belly. Mature males have a darker color on the belly. They have no scales. The mouth is square, and positioned right at the end of the snout. The anal fin extends the length of the body to the tip of the tail. As in other ostariophysan fishes, the swim bladder has two chambers. The anterior chamber is connected to the inner ear by a series of small bones derived from neck vertebrae called the Weberian apparatus which greatly enhances their hearing capability. The posterior chamber extends along the whole length of the body and is used in buoyancy. Electrophorus has a well developed sense of hearing. Electric eels have a vascularized respiratory organ in their oral cavity (Albert, 2001). These fish are obligate air-breathers; rising to the surface every 10 minutes or so, the animal will gulp air before returning to the bottom. Nearly 80% of the oxygen used by the fish is taken in this way. Despite its name, the electric eel is not closely related to true eels (Anguilliformes) but is a member of the Neotropical knifefishes (Gymnotiformes), more closely related to catfishes.
Physiology
The electric eel has three abdominal pairs of organs that produce electricity: the Main organ, the Hunter's organ, and the Sachs organ. These organs comprise four-fifths of its body. These organs are made of electrocytes, lined up so that the current flows through them and produces an electrical charge. When the eel locates its prey, the brain sends a signal through the nervous system to the electric cells. This opens the ion channel, allowing positively-charged sodium to flow through, reversing the charges momentarily. By causing a sudden difference in voltage, it generates a current. The electric eel generates its characteristic electrical pulse in a manner similar to a battery, in which stacked plates produce an electrical charge. In the electric eel, some 5,000 to 6,000 stacked electroplaques are capable of producing a shock at up to 500 volts and 1 ampere of current (500 watts). The organs give the electric eel the ability to generate two types of electric organ discharges (EODs), low voltage and high voltage. The shock could be deadly for an adult human.
The Sachs organ is associated with electrolocation. Inside the organ are many muscle-like cells, called electrocytes. Each cell can only produce 0.15V, though working together the organ transmits a signal of about 10V in amplitude at around 25 Hz. These signals are what is emitted by the Main organ and Hunter's organ that can be emitted at rates of several hundred Hz. These high voltage EODs may reach up to 650 volts. The electric eel is unique among the gymnotiforms in having large electric organs capable of producing lethal discharges that allows them to stun prey. There are reports of animals producing larger voltages, but the typical output is sufficient to stun or deter virtually any other animal. Juveniles produce smaller voltages (about 100 volts). Electric eels are capable of varying the intensity of the electrical discharge, using lower discharges for "hunting" and higher intensities for stunning prey, or defending themselves. When agitated, it is capable of producing these intermittent electrical shocks over a period of at least an hour without signs of tiring. The species is of some interest to researchers, who make use of its acetylcholinesterase and ATP. The electric eel also possesses high-frequency sensitive tuberous receptors patchily distributed over the body that seem useful for hunting other Gymnotiformes. Electric eels have been widely used as a model in the study of bioelectrogenesis.
Bionics
Researchers at Yale University and the National Institute of Standards and Technology (NIST), applying modern engineering design tools to one of the basic units of life, argue that artificial cells could be built that not only replicate the electrical behavior of electric eel cells but in fact improve on them. Artificial versions of the eel's electricity generating cells could be developed as a power source for medical implants and other tiny devices.
Habitat
Electric eels inhabit fresh waters of the Amazon and Orinoco river and the basins in South America, in river floodplains, swamps, coastal plains, and creeks. They tend to live on muddy bottoms in calm water and in stagnant arms of rivers.
Feeding ecology
Electric eels feed on invertebrates, while adult eels feed on fish and small mammals. First-born hatchlings will even prey on other eggs and embryos from later batches. The younglings will eat invertebrates such as crab and shrimp. When they reach adult hood they consume amphibians and occasionally birds.
Reproduction
The electric eel is also known for its unusual breeding behaviour. In the dry season, a male eel makes a nest from his saliva into which the female lays her eggs. As many as 17,000 young will hatch from the eggs in one nest.
In zoos and private collection
These fish have always been high on the list of brave animal collectors, but catching one isn't easy, so the only option was to make the eels tire themselves with continual discharging. Some unlucky horses or mules were driven into a pool of water harbouring the fish and there they received enough shocks to at least knock them out. The fish's batteries would eventually drain allowing the collectors to wade into the water in comparative safety.
Taxonomic history
The species is so unusual that it has been reclassified several times. Originally it was given its own family Electrophoridae, and then placed in a genus of Gymnotidae alongside Gymnotus. Electric Eels will not be found in salt waters, due to the salt having a protonic effect on the eel's charge causing it to naturally short-circuit.

The Copperband Butterflyfish, also known as the Beaked Coralfish is one of three species in the Chelmon genera, all of which are noted for having longer beaks. This pretty butterflyfish is commonly available and is reasonably priced. However it is delicate and the ease of keeping this species varies from one fish to another. Some will be easily adapted and maintained while others refuse foods and perish. The best success in keeping this species is in choosing a healthy well fleshed out individual, avoiding any that look emaciated. It is reported that those from Australia may do better than those from other areas, possibly reflecting methods of collection and transport, and they usually cost a bit more.
The Copperband Butterflyfish can do well with a variety of other less aggressive species in a fish only community tank. It is aggressive towards others of its own kind and possibly towards other Chelmon species. It will usually be fine with other butterflyfish species but an occasional adult may become aggressive. Keeping this butterflyfish in a reef environment however, is a judgment call. Success will depend on what other types of reef inhabitants you are keeping, as well as your individual Copperband Butterflyfish's tendencies. They are not generally coral feeders, but may nip at the polyps of large polyp stony corals...and they enjoy polychaete worms.
Habitat: Natural geographic location:
The Copperband Butterflyfish or Beaked Coralfish was described by Linnaeus in 1758. It was first collected in the Indian Ocean and was described as Chaetodon rostratus. They are found in the Northeastern Indian Ocean and the West Pacific; Andaman Sea to the Ryukyu Islands, Southeast Asia to the Great Barrier Reef, Papua New Guinea and the Solomon Islands. One record of an adult specimen from southern Honshu, Japan was made but it seems a waif from the Ryukyu Islands or perhaps was due to an aquarium release.
In their natural habitat they are observed singly or as a pair of adults in coastal and inner reefs, and also estuaries. Juveniles can be observed alone or in a small group. This species dwells at the depths between 3 - 82 feet (1 - 25 meters).
Status:
These fish are not listed on the IUCN Red List.
Description:
The body of the adult Copperband Butterflyfish is silvery white overall with four vertical orange bands on the side, each with a blackish edge. The first passes through the eye and the last is obscured on the top and bottom. The dorsal and anal fins are white, edged in yellow with a bluish submarginal line. The body bands extend across the fins and there is a black ocellus in the upper portion of the last band that has a bluish white circle basally. The caudal fin is whitish fading to translucent, and there is a vertical black line on the peduncle with an orangish band just behind the black. The pelvic fins are orange with a vertical white bar centrally.
Juveniles are very similar but the ocellus on the dorsal fin is larger, and the orange bars are more conspicuous with each edged by black.
The Copperband Butterfly is very similar in appearance to its close relative the Margined Butterflyfish C. marginalis. As adults these two species can be differentiated by their color pattern, however as juveniles they are virtually identical. As the Margined Butterflyfish matures, the narrow mid body bar disappears and the ocellus becomes obscure. It is thought that these two species may hybridize in areas where they co-occur.
Length/Diameter of fish:
Adults reach 7.8 inches (20 cm), but most specimens available are are less than 5 1/2 inches (14 cm).
Maintenance difficulty:
Keeping the Copperband Butterflyfish varies between the individuals. Some will quickly accept fresh and frozen foods and be easy to maintain. Others will refuse to eat initially, but may be enticed to eat live foods offered in a way that simulates their natural feeding environment. Yet still, other individuals will refuse foods entirely and ultimately perish. Juveniles tend to accept various foods and so can often be more adaptable to aquarium life than adults.
Many of the Chaetodon members are often very colorful and attractive to aquarists. Unfortunately some of them are rather difficult to keep for a long period. Some are exclusively coral eaters, and sometimes they suffer from “ich” (white spot disease) and other infectious diseases.They can be treated successfully with medical care or copper drugs, but some species hate sudden changes of water including PH, temperature, or any drug treatment.
The Copperband Butterflyfish will often suffer from Lymphocystis. Many can be treated successfully with medical care or copper drugs, though severely infected specimens will not survive.
In the wild a cleaner wrasse (Labroides sp.) will help them by taking parasites from their bodies, however these wrasses are extremely difficult to sustain in captivity. Alternative fish such as Neon Gobies (Gobiosoma spp.) can help them by providing this cleaning service in the home aquarium.
Social Behaviors:
Keeping the Copperband Butterflyfish in a reef environment is a judgment call. Success will depend on the individual fish as well as what types of reef inhabitants you are keeping. In his excellent book, Angelfishes & Butterflyfishes: Reef Fishes Series, author Scott W. Michael says that many of the soft corals with the exception of some of the zeniids, clavularids, and zoanthids can be fine, and also many small polyped stony corals though it may nip on the large polyped stony corals. A pro to keeping it in a reef tank is that some individuals will munch on those pesky Aiptasia species, the glass anemones. A con to keeping it in a reef is that polychaete worms are a favorite (and natural) food, and it will most likely have a heyday with them. Many aquarists report that when kept well fed, their Copperband Butterflyfish doesn't bother any of their reef species.
It can do well in a large fish only community tank that is well decorated with large furnishings such as table corals where it can rest and lie motionless. It is a not an overly aggressive fish, but it is territorial and will be aggressive towards other members of its own kind, and sometimes other butterflyfish in its same genus, Chelmon. Not-so-aggressive angelfish like members of Centropyge, Apolemichthys, Genicanthus, Chaetodontoplus and Pygoplites can be good tank mates. Smaller, non-aggressive fishes like cardinalfish, gobies, tilefish, sometimes other species butterflyfish, fairy basslets, fairy and flasher wrasses, etc. also are good candidates as tank mates.
It may not do well with large or aggressive fish. Seeing it dart into hiding is a good indication that it is feeling threatened and the situation may need to be remedied with one of the fish being removed. The large and rather territorial angelfish, Pomacanthus and Holacanthus should be avoided as should most damselfish species. Small but very territorial fishes like dottybacks should also be avoided as well as such fish as basses or scorpionfish, even if they are small.
Sex: Sexual differences:
No sexual difference is noted for this species. Butterflyfish species studied up to this time indicate that these fish are gonochoristic, meaning that each fish is either a male or a female and they do not change sex.
Breeding/Reproduction:
This species has not been cultivated in captivity. Marine butterflyfish have not reportedly been spawned successfully in captivity. There are, however, reports of some success in rearing wild collected larvae of some of the corallivorous butterflyfish. It is hoped these captive reared fish will be adapted to accept aquarium foods, and thus broaden the species selections that can be sustained in captivity.