The Neon Tetra is a brightly colored small fish. They rarely exceed four cm in length, averaging one and a quarter to one and a half inches in length, with males being slightly smaller than females. Females also have a rounded belly, while males are described as being more 'straight'. They are named 'neon' because the blue green line that runs from their eye to their tail reflects in a way similar to neon. The female's line will have a noticeable kink in it. The function of this line is to allow other Neon Tetras to see each other in dim or dark waters. The effect of this line in an aquarium is nothing less than beautiful, particularly when they are schooling. The body of the Neon is brightly colored, with a silver fronted lower body. Their fins are typically clear, though the base of the caudal fin is a brilliant red.

The Thorny Devil is a moderately sized lizard, averaging between 15 and 20 centimeters (about six inches) in length. They are covered in thorny spikes and grooved skin. They have a knob resembling their head on their back, which they expose when threatened. The Thorny Devil's tongue is very sticky and fast moving, unlike the rest of the lizard, which moves quite slowly. Many people believe the Thorny Devil resembles a miniature rhinoceros.

Black Sharks are large fish that average 20 to 24 inches in length, though individuals as large as 2 feet have been documented. Male and females are not visually distinct, and this is one reason why captive breeding is difficult.

Chinese Water Dragons are lovely green lizards that appear to be mostly tail: the striped brown and green tail makes up about three-quarters of its full length. Males grow to be about three feet and females about two feet long, though some females can grow as larger, or larger than males. They are green with vertical stripes of a contrasting green color.Green Water Dragons have colorful throats, ranging from pink or peach to brighter shades of orange. They have triangular heads and a small shiny spot between the eyes, which Water Dragons use to thermo-regulate and sense light. The hind legs are more muscular than the slim front legs, and like us, Water Dragons have five toes. They have sharp claws and the middle toe is the longest toe. It is difficult to visually distinguish between the sexes and nearly impossible until the Water Dragon is sexually mature, though generally males are larger and have more pronounced heads and jowls.

At maturity, female Sand Lizards usually measure about 8.5 inches (22 centimeters) in length, and males often reach lengths of 10.5 inches (27 centimeters). Their bodies are robust in shape and the tails and heads are rather short and blunt. Although females are less brightly colored than males, both sexes of Sand Lizards have two well-defined dorsal stripes amid an oscillated dark brown and white patterning. A band of smaller scales is also present over the back. Between April and May, male Sand Lizards acquire brilliant green coloring over their normally plain green sides.

The Sudan Plated Lizard averages around 18 inches in length, with half that length being its tail. They range between 16 and 28 inches when full-grown. TheSudan Plated Lizard has a very strong, muscular body that is slightly flat. Their legs are small relative to their body size. The scales of theSudan Plate Lizard have raised ridges (keels) on the dorsal surface scales and are smooth elsewhere. The Sudan Plated Lizard can be found in almost all shades of brown, from yellow to quite dark, and often have lighter markings.

At maturity, the Platy will reach a size of two to three inches. They have stocky, fat, stubby bodies with a rounded caudal fin. Their bodies are usually a mixture of red, yellow, gold, black and blue. Younger Platys are usually brighter.

These are tall fish which give the appearance of a Red-bellied Piranha (Pygocentrus nattereri but they tend to be somewhat plumper despite the fact that the two are often confused. The most significant morphological difference between the two is the the level of protrusion of the jaw (much smaller in pacus than in piranhas). This helps to illustrate the largely vegetarian nature of the pacu and the largely carnivorous nature of the piranha. They are either grey or silvery fish with red bellies and the pacu has red lower body fins as well. The tambaqui also grows to a size which Pygo. nattereri can never hope to achieve. The genus to which the tambaqui formerly belonged, Colossoma was, at the time, the only genus of fish in which true molars are present. All genera which sprang from Colossoma are now among that still-somewhat-small assortment. Though they aren't to be feared as much as piranhas, tambaquis have formidable teeth which will be used on careless keepers that anger or scare them. The name Serrasalmidae means "Salmons with a Saw" (David Schleser, "Piranhas: A Complete Owners' Manual"), and this accurately describes the dentition of the Pacus.