Ask the WWM Crew
|Please visit our Sponsors|
In the giant collection of fishes that are the minnows, there are species and sub-groupings that are real stalwarts in the aquarium interest. Where would we be without the various "sharks" and peculiar gudgeons, or goldfish and koi in all their varieties? Not to mention all the important food and forage minnow species in the wild. Here we'll cover three of the most important assemblages of minnows used by freshwater hobbyists; the Barbs, Danios and Rasboras, and give an overview of the entire minnow family.
Like the African cichlids of different lakes, Rainbowfishes and Gouramis, each of these minnow groups has had its heyday; with aquarists anxiously following the latest discovery or breeding report of new species. But don't get me wrong; these fishes are far from passe; for hardiness, color and action, there are sizes, shapes and finnage for all freshwater set-ups. And new varieties, especially color variants, are constantly being developed.
Due to their close taxonomic affiliation, these three minnow sub-groupings can be described and understood for their similar care and husbandry.
Classification: Taxonomy, Relation With Other Groups
Barbs, Danios and Rasboras all belong to the minnow family, Cyprinidae ("Sigh-prin-id-ee"). Cyprinids are the largest family of fishes, with about two hundred ten genera and over two thousand species (2189 currently according to www.fishbase.org).
What do you picture when you think of a general minnow body-plan? They're generally small, high-backed and compressed side-to-side; with snouts that are typically short supporting a terminal or under-slung mouth.
Minnows have further defining characteristics. Their jaws lack teeth entirely; instead they utilize pharyngeal teeth further down in the throat to grind their food. Aiding their typical plant and bottom feeding is a protrusible mouth and tactile and chemo-sensory barbels; usually in two pairs. They have dorsal, anal and ventral finnage that complement of paired fins, pectorals and pelvics; but lack an adipose. Most have simple cycloid scales covering their bodies, but heads that are scaleless. Their gas bladders are divided into two or three chambers.
Species of Use/Availability to Aquarists:
Barbs; the common name comes to us from the original designation by Bleeker, placing these fishes in the genus Barbus. There is a still-disputed sub- and alternate classification scheme roughly based on the number of barbels; Barbodes (4); Capoeta (2); and Puntius (none); but this system is not consistent.
Barbs come in two general classes behaviorally; the smaller, peaceful variety, and the fin-nipping, zooming around boisterous kinds. Of the previous, the gold, checkerboard and gold barbs serve as delightful paradigms. The latter includes tiger, tinfoil, T-bar and many more. For these go-getting, fin-biters a few words of advice: 1) Do keep them with other fast-moving, and/or medium-aggressive fishes; larger Gouramis, semi-peaceful cichlids, equal-temperament Characoids like the larger Pencilfishes... 2) Stock and maintain them in small, odd-numbered schools; 3, 5, 7... this non-even arrangement tends to reduce aggression between the barbs and their tankmates. 3) Provide plenty of cover in the way of plants and decor.
Though they're not as popular in the United States as elsewhere, there are three dozen or so species of barbs and many finnage and color variants used in the hobby worldwide. Here are notes on the most commonly encountered. None are from Africa.
My favorite barbs are the smallest ones, which also happen to be the most peaceful. The Cherry Barb (Puntius titteya), Checkered or Checkerboard (Puntius oligolepis), and Gold or Golden Barb (Puntius sachsii) are great small (about an inch) additions to community tanks.
Medium-sized varieties like the Tiger Barb (Puntius tetrazona), Rosy Barb (Puntius conchonius), Clown Barb (Puntius everetti), Black Ruby Barb (Puntius nigrofasciatus), Arulius Barb, (Puntius arulius) Five and Six-Banded Barbs (Puntius pentazona & Puntius hexazona respectively) are best kept with medium sized Gouramis, Botias, easy-going medium-sized Cichlids...
The larger barbs like Spanner (Puntius lateristriga), Black-Spotted (Puntius filamentosus) and Tinfoil (Barbodes schwanenfeldii) need real room to move. Tinfoil Barbs will be crowded in anything less than a four foot long tank.
Danios and Rasborasare so closely related that taxonomists place them together in a Subfamily of their own, Rasborinae within the Family Cyprinidae. This subfamily also includes another standard "bread and butter" aquarium species, the White-Cloud Mountain Fish, Tanichthys albonubes. Named by Henry Fowler for his porter (named Tan of course) this is another great community fish.
Danios are amongst the hardiest fishes the hobby has to offer; these are the quintessential beginning aquarists fishes. These fishes too should be kept in groups in as large a system as possible, minimum of twenty gallons.
Of the genus Danio (many formerly Brachydanio), there's long and short finned varieties of Zebra (Danio rerio), Pearl (Danio albolineatus) and Leopard (Danio frankei) Danios; and the occasionally seen Spotted Danio, Danio nigrofasciatus. Larger members include the standard Giant Danio (Danio malabaricus) and the deeper-bodied Danio aequipinnatus
Rasboras number some 50 species in the genus Rasbora alone plus a few in other genera. These are small minnow fishes; most are an inch or so, though a few relative giants approach half a foot in length. All are great for general community aquariums.
To many Rasbora heteromorpha is "the" Rasbora. Also known as the Red Rasbora or Harlequin, this fish now is available in an attractive blue variation. Occasionally you might find the Scissor-Tail Rasbora, Rasbora trilineata; otherwise, unfortunately few other species are regularly if ever offered in the retail trade in the west.
Natural and Introduced Range
Though a few species of Barbs are found in Africa, the Far East and India are the principal home of the Danios, Barbs and Rasboras. None are found in North, Central or South America; or Australia.
Some of the smaller Rasboras top out at half an inch; I've seen Tinfoil Barbs over a foot long.
Selection: General to Specific
1) Number: Remember that most of these fishes are schooling species; they only feel at ease and act naturally when housed in a large enough system in groups. Three individuals is an absolute minimum, with larger, odd numbers being better.
2) Space and Spatial Preference: A note here to set aside enough room for everyone and to bear in mind that a given species tends to occupy particular depths. Most Barbs are bottom dwellers, Danios the top, and Rasboras the middle.
3) Time at the Dealers: Important as some shipments of these fishes succumb to apparently nothing more than shipping stress. Make sure they've been at your sources a good three days before taking them on.
4) Behavior: Healthy specimens are out and about, looking for food all day long. Tanks with specimens hiding in the corners are coming down with something or going out due to poor water quality.
By and large these fishes prefer a system of subdued lighting and live plants. Now, I can hear the knowledgeable Reader exclaiming to themselves, "they'll eat the plants". Well, yes to an extent these fishes will, and they probably need them in their diet. If there's an abundance of plant eaters or a paucity of plants, sure, your plants will be nibbled till gone. What I'm encouraging here is a mix of some fish and lots of plant material. However, should you have some real greens-gobblers, do consider at least a set up with a glass divider between your plants and fishes, with some plant material offered as food.
For appearance sake I suggest you employ a dark-colored gravel base. This will show off these iridescent beauties at their best.
Oh, and we should mention, these fishes are some of the best jumpers in the hobby. Keep your tank(s) completely covered, quarantine, hospital and spawning included.
Due to being bred in captivity for so many generations and their natural tolerance, these minnow-fishes are tough to a wide range of conditions. Though most species prefer soft, acidic water they've been reared and spawned in the widest tap-water parameters.
More important than any given set of temperature and chemical conditions, it is important to beware of fast changes in their waters makeup. A regular routine of frequent partial water changes (ideally 25% weekly) will grant your fishes long, healthy lives.
Most of these fishes live in fast moving streams and waterfall areas and appreciate the currents and oxygen that comes with vigorous water movement. For small tanks an inside power filter might be best; larger ones call for the redundant use of two or more outside hang-on or canister power filters.
Not really territorial per se but amongst their species some individuals can become a real bother to a smaller conspecifics. This is the reasoning behind keeping them in odd numbered schools.
Barbs, Danios and Rasboras do poorly when exposed to "new-tank" conditions; e.g. one's going through nitrogen cycling. Therefore they should only be placed in established systems. If possible all should be about the same size to start with and be put in at the same time. The larger species of these groups ought to be introduced later into the system, after their tankmates.
For all but the smallest Barbs and Danios, putting them in with slow moving, long-finned companions is asking for trouble. Why do they pick on such sluggard tankmates? To get them out of the way? Out of boredom? Because they can? Who knows, but they will. Angels and Bettas beware.
Other predatory fishes large and fast enough to catch and eat minnows will do just that.
Reproduction, Sexual Differentiation
Some of these fishes display sexual dimorphism, structural differences between the sexes, with males being longer finned, slimmer and more tapered overall. All show a degree of color changes, especially the males, during spawning season.
Purposeful spawnings take the following general plan. Fish are conditioned to fitness separated by sex or not. Spawners are moved to a designated spawning tank with natural or not media (mops, Java moss...) more with one or two males per female. Some folks use coarse gravel, glass marbles, or a network of rods, etc. to separate the parents from their spawn (they are egg and young-eaters). The young are left to hatch out in 1-2 days.
The very small free-swimming fry are fed on very fine food (infusoria/rotifers, egg-yolk formulated tube or dried foods, brine shrimp nauplii) in another day or two. A sponge filter and daily water changes with conditioned water optimize results.
Feeding/Foods/Nutrition: Types, Frequency, Amount, Wastes
All of these minnows readily accept every type of fish food, live or prepared. A good staple of dried-prepared food will keep them in good stead, with daily to weekly offerings of fresh, either live or frozen-defrosted. Additionally, some sort of green food should be part of their diet every day.
Want to grow your minnow-fishes up big, fast? Do what commercial interest do; feed small amounts several times a day, maybe by way of an automatic feeder. Plus adequate circulation, aeration, filtration and frequent partial water changes to flush out growth-limiting metabolites.
If familiar food is refused by these fishes, check your system and water, something is definitely amiss.
Disease: Infectious, Parasitic, Nutritional, Genetic, Social
These minnow fishes are usually resistant to disease once properly acclimated and kept in a stable, regularly maintained environment. Unfortunately, as freshwater aquarium species go, the Barbs, Danios and Rasboras are easily susceptible to parasitic infection; in particular to white spot disease and velvet.
Ichthyophthiriasis and Oodiniumiasis are quickly brought on by rapid drops in temperature or careless introduction of a hyper-infection with new introductions, and must be dealt with quickly. If the other livestock (including plants if present) can tolerate it, non-iodized salt plus standard remedies work well. Take care to increase aeration if you're raising the temperature, and remove chemical filtrants during treatment.
What more do aquarium hobbyists want in their livestock? The Danios, Rasboras and Barbs are hardy, beautiful, active, easy to breed and peaceful for the most part, and because of all these traits, relatively inexpensive and readily available.
I know "if wishes were fishes we'd all have full tanks"; but I really do hope that more aquarists will become local suppliers of these fishes as time goes by. Breeding and raising them quickly can be not only fun, but can be quite profitable; increasing local supplies while cutting down on imports. Consider trying your hand at breeding these fishes.
Anon. 1974. Delightful and unusual rasboras. Aquarium Digest Intl. 2(3):74.
Axelrod, Herbert R. 1954. Breeding the rasbora. TFH 2(3):1954.
Axelrod, Herbert R., Warren E. Burgess, Neal Pronek & Jerry G. Walls. 1990. Atlas of
Aquarium Fishes Reference Book, v.2, Freshwater Fishes. T.F.H. Publications, Inc. NJ. 1055pp.
Baensch, Hans A. & Rudiger Riehl. 1993. Aquarium Atlas, v.2. BAENSCH, Germany. 1212pp.
Batory, Dana M. & Todd L. 1984. Spawning the zebra danio. FAMA 11/84.
Batory, Dana Martin. 1985. Spawning the cherry barb. FAMA 11/85.
Brittan, Martin R. 1971. Rasbora; a revision of the Indo-Malayan freshwater genus Rasbora. T.F.H. Publications, NJ. 224 pp.
Brittan Martin R. 1984. The rasboras. TFH 9/84.
Dawes, John. 1998. Introducing the Barbs. Very popular, and most are of aquarium size. AFM v5/98.
Dawes, John. 1999. The Danios. Introducing one of the true delights in the hobby. AFM 11/99.
Elias, Jaroslav & Frantisek Podvesky. 2000. Rasbora heteromorpha, Harlequin Rasbora. TFH 4/00.
Gibbs, Max. 1998. Rasboras. Is this the perfect community fish? AFM 1/98.
Glass, Spencer. 1997. Tin soldier. TFH 6/97.
Hunziker, Ray. 1988. The delightful danios. TFH 8/88.
Hunziker, Ray. 1996. Rasboras; attractive Asians for the community aquarium. TFH 1/96.
Jonklaas, Rodney. 1988. New! A blue variety of the gold barb! TFH 3/88.
Mayland, Hans J. & Dieter Bork. 2000. The genus Danio. TFH 5/00.
Nelson, Joseph S. 1994. Fishes of the World. John Wiley & Sons, NY. 600pp.
Norton, Joanne. 1994. Tiger bard genetics. FAMA 9/94.
Ong, Y.W. 1959. This fish is a sun-worshiper (Malayan fish of the genus Puntius). TFH 1/59.
Palicka, Jiri. 1988. Barbodes ablabes- the long-striped barb. TFH 8/88.
Riehl, Rudiger & Hans A. Baensch. 1996, 5th rev. ed. Aquarium Atlas, v.1. MERGUS, Germany. 992pp.
Riehl Rudiger, & Hans A. Baensch. 1996. Aquarium Atlas, v.3. MERGUS, Germany. 1104pp.
Sterba, Gunther. 1966. Freshwater Fishes of the World. The Pet Library , Ltd, NY. 879pp.
Walker, Braz. 1981. Black spotted barb. FAMA 1/81.
Wilkerson, Jennifer. 1999. Black ruby barbs, Puntius nigrofasciatus. TFH 11/99.
Zukal, R. & S. Frank. 1981. The leopard danio; hybrid, mutant or valid species. TFH 7/81.