The zig-zag eel also known as the tire-track eel, tire-track spiny eel or marbled spiny eel,Mastacembelus armatus, is a species of ray-finned, spiny eels belonging to the genus Mastacembelus of the family Mastacembelidae, and is native to the riverine fauna of India, Bangladesh, Pakistan, Sri Lanka, Thailand, Vietnam, Indonesia and other parts of South East Asia. The species was described as Macrognathus armatus by Lacepède in 1800. Other common names for this popular aquarium species are leopard spiny eel and white-spotted spiny eel. This species is not only a popular aquarium fish but also as a food fish in its country of origin Mastacembelus armatus is a large elongated fish that has a snake-like body without pelvicfins. Its anal and dorsal fins are elongated and are connected to the caudal fin. The dorsal fin is preceded by numerous spines. The back is dark beige in color while the head is silver-beige. The body's color is dull brown and the belly is a lighter shade of brown. The body may also be marked with brown circular patterns. The body also have one to three darker longitudinal zigzag lines that connect to form a distinct reticulated pattern that is restricted to the dorsal two-thirds of the body. The eyes have brown stripes running laterally through them. Mastacembelus armatus can reach up to 36" (91 cm) in its natural habitat but does not usually exceed 20" (51 cm) in captivity. Despite its eel-like appearance, Mastacembelus armatus is not considered a true eel. Mastacembelus armatus are nocturnal fish that thrive in highland streams, lowlandwetlands, still waters, coastal marshes and rivers with sandy or rocky riverbeds and heavy vegetation. They are common during the tropical summer months and will dwell in canals, lakes and other floodplain areas during the flood season. Being nocturnal carnivores, zig-zag eels forageon benthic insect larvae, earthworms, blackworms and some submerged plant material. In an aquarium setting, they require live foods in their diet such as live fish, tubifex worms, brine shrimps, mosquito larvae, frozen bloodworms, cyclops, krill and ocean plankton. Although zig-zag eels are often combined with medium to large-sized gouramis, knifefish, danios, loaches, Loricariids, eartheaters, acaras, Cichlasomines and Asian catfishes in a community fish aquarium, they are not normally mixed with small-sized fish, because tire track eels are observed to prey upon smaller fish. Mixing them with fish belonging to the same species is also not recommended. This is because they are aggressive to members of the same fish family but peaceful to other fish species with similar care level requirements, size and temperament.

Anguilla bengalens is, the Indian mottled eel, is a subspecies of eel in the genus Anguilla of the family Anguillidae. It is found throughout the Indian subcontinent and neighbouring regions including the East Indies. Showing the typical characteristics of the Anguillidae, this species grows to 1.2 m and as much as 6 kg Indian Mottled Eel range expands from East Africa rivers and coastal areas across the Indian Ocean to mainland India, Pakistan, Bangladesh, Indonesia and Malaysia, and is an occasional visitor to the Arabian Peninsula. Indian Mottled Eels inhabit various niches in river systems, their habitat expands from, quiet, undisturbed areas containing mud substrate to deep water, fast-flowing rock pools of rivers

chitala is a knifefish from Bangladesh, India, Nepal, and Pakistan, found in the Brahmaputra, Indus, Gangesand Mahanadi River basins. It is sometimes known as the Indian featherback or Indian knifefish.In the past, it frequently included several related Chitalaspecies, but these are now regarded as separate species.The main species confused with this species is C. ornata (clown featherback or clown knifefish); a Southeast Asian species seen regularly in the aquarium trade. The true C. chitala is very rare in the aquarium trade. chitala in Assam, India: Notice the stripes on the back and the dark spots on the lower rear part of the body (both relatively indistinct) chitala reaches a maximum length of 122 cm but more commonly reaches about 75 cm . It is overall silvery in color. Unlike all its relatives, it usually has a series of golden or silvery bars along the back, resulting in a faint striped appearance. Additionally, it has a series of fairly small, sometimes indistinct, nonocellated dark spots towards the far rear of the body (at the "tail"). This separates it from C. ornata, which has ocellated spots (dark spots surrounded by a paler ring) and lacks bars along the back. The two species have frequently been confused.