About the Giant Danio
Species Type: Freshwater Fish
Care Level: Moderate. May tolerate only a narrow range of water parameters, have specific dietary requirements including frozen or even live foods, may have behaviors that severely limit potential tankmates or may require a specialized aquarium setup.
Origin: SE Asia: Northern India, Nepal, Bangladesh, Myanmar and Thailand. Found in moderate-flow clear streams and rivers with gravel and pebble substrates and shaded by overhanging vegetation.
Compatibility/Temperament: A shoaling fish that must be kept in a group due to its high level of interaction; 8 is considered the minimum number. Their activeness makes them unsuited to any slow or sedate fish, and they are best with medium/larger danio, peaceful barbs, and loaches. Several sources mention their boisterous aggressiveness including fin nipping, and this will more likely be curtailed and confined to "play" if a group of 8 or more are kept in a 4+ foot tank with suitable tankmates. These fish are jumpers, so a tight cover is a must.
Most of the more than 30 valid species in the Devario genus are unknown to aquarists. There are several species that attain the 4-6 inch size, and any of them may be offered under the common name of Giant Danio. The subject species is the one most frequently encountered in the hobby. This species is similar to the more common Danio rerio [Zebra Danio], but larger and rather more boisterous as noted under Compatibility. It has a lifespan of 5-7 years.
Lioke all danionins [a useful name for the species in Danio and Devario], it is a very active swimmer, preferring the middle and upper regions of the aquarium. A suitable aquascape would be a long tank (at least 4-feet) with a substrate of gravel and pebbles, and a moderate flow from the filter whose outflow should be placed at one end of the tank to provide the natural current of a stream. Plants along the back are appropriate, and floating plants or overhanging vegetation will replicate the fish's habitat.
Males are a bit more colourful and slightly smaller than the rounder females. Like most cyprinids, this species is an egg scatterer and shows no parental care of eggs or fry; it is an easy spawning fish in aquaria.
Upon being initially described in 1839 by J. McClelland, the assigned name was Perilampus aequipinnatus. In 1981 the species was transferred into the genus Danio where it remained until Fang (2003) sorted things out [see following].
The danionin is a group of minnow-like fish within the family Cyprinidae. All discovered species were originally placed in the genus Danio until Dr. George S. Meyers (in the early 20th century) divided them into three genera, Danio, Brachydanio and Daniops. During the latter two decades of the twentieth century, many ichthyologists had doubts about the validity of Brachydanio, and in 2003 Dr. Fang determined that the genus Danio was paraphyletic [Greek para = near and phyle = race], which means the genus contains its most recent common ancestor but does not contain all the descendants of that ancestor. Danio was restricted to the nine species of the Danio dangila group comprised of the smaller-sized species, and the genus name Devario was suggested for the remaining larger-sized species. The former genus Brachydanio was disbanded.
Several further developments in research occurred in the subsequent years, and their findings largely supported Dr. Fang's results. Mayden et.al. (2007) also recognized the close relationship of Microrasbora species to those of Danio. We follow Dr. Fang's placement, though many speculate that the clades may end up as distinct genera.
In Joseph S. Nelson's "Fishes of the World" (2006), Danioninae was listed as a synonym of Rasborinae. It is generally held (though some disagree) that there are three clades within the genus Danio, and the danionin genera are within the Sub-Family Rasborinae [the name having priority over Danioniae] along with several genera of rasborin. The danionins can be classed as a subfamily Danioninae which has increasingly been gaining credibility as a distinct subfamily from Rasborinae within the Cyprinidae family; this is now accepted by the California Academy of Sciences.
Fang, Fang (2003), "Phylogenetic Analysis of the Asian Cyprinid Genus Danio (Teleostei, Cyprinidae)"
Fang, Fang, M. Noren, T.-Y. Liao, M. Kallersjo and S. O. Kullander (2009), "Molecular phylogenetic interrelationships of the south Asian cyprinid genera Danio, Devario and Microrasbora (Teleostei, Cyprinidae, Danioninae)," Zoologica Scripta v. 38 (no. 3), pp. 156-237.
Mayden, Richard L., Kevin L. Tang, Kevin W. Conway, Jorg Freyhof, Sarah Chamberlain, Miranda Haskins, Leah Schneider, Mitchell Sudkamp, Robert M. Wood, Mary Agnew, Angelo Bufalino, Zohrah Sulaiman, Masaki Miya, Jenji Saitoh, and Shunping He (2007), "Phylogenetic relationships of Danio within the order Cypriniformes: a framework for comparative and evolutionary studies of a model species."
Ruber, Lucas, Maurice Kottelat, Heok Hui Tan, Peter KL Ng, and Ralf Britz (2007), "Evolution of miniaturization and the phylogenetic position of Paedocypris, comprising the world's smallest vertebrate."
Giant Danio Diet
Naturally feeds on exogenous insects, crustaceans and worms. Accepts most prepared foods readily; dried flake and granular can be supplemented with frozen bloodworms, brine shrimp, daphnia, live worms.
Most sources give 4 inches as the maximum, but some indicate 5-6 inches.
Minimum Tank Suggestion
48 inches in length; a 55g or larger.
Ideal water parameters for Giant Danio
Soft to medium hard (hardness 5-20 dGH), slightly acidic to basic (pH 6 to 8), temperature 22-25C/71-77F.