To Gold or not Too Gold, That Is The Tetra

Hemigrammus rodwayi is commonly called either the Brass or Gold Tetra. When you look at these fish in most fish stores, you'll wonder why, as they are usually silver, with black and red highlights at the base of their caudal fin, with maybe the slightest hint of gold (or brass) along their backs and in a bar down their side. There is good reason for this discrepancy.

The wild range of Hemigrammus rodwayi is much of northeast South America where they are found in the river systems of Suriname, Guyana, French Guiana, and Brazil's Amazon basin. They are most frequently found in coastal ares of these rivers, and are no strangers to brackish environments. The rivers are generally slow moving, strongly colored and thus dimly lit. These same rivers are also home to a parasite called a trematode that the Gold Tetra is prone to infection from. This infection actually causes a skin condition in the Tetra and turns them a brilliant burnished gold / brass color. This parasite is missing from the aquaculture facilities that produce these fish, and so the specimens that you get from them will only have hints of gold. With this in mind, its pretty easy to see when you are buying aquacultured specimens or wild caught individuals.

There are benefits to buying both ways. The aquacultured specimens are much hardier and still beautiful in their own right, even if their names are a tad misleading. The wild specimens offer a coloration that is extraordinarily rare in aquarium keeping. Regardless of which you choose, they should always be kept in groups of at least ten. Hemigrammus rodwayi is a very timid fish, and will be bolder, and actually healthier if kept in a group. These are small fish, rarely reaching two inches long, and so maintaining them in schools doesn't require a ridiculous tank size. A group of this size could easily be kept in a 20-gallon tank.

In regard to water quality, these Gold / Brass Tetras need very soft water and a low pH. Shoot for hardness less than five dgh and pH between 5.5 and 6.5. The water should be warm, 78-82 degrees Fahrenheit. Most aquarists will start with RO (reverse osmosis filtered) water for these displays to ensure a water profile that is soft enough to start with, and free of buffers to make it easy to dial in an appropriate pH.

These fish do well in dimly lit displays that are stained to some degree. This tea-colored water will also enhance the golden / brassy color of even the aquacultured individuals. They are perfect candidates for leafy bottom tanks (check out our forager article) with a good amount of driftwood. Many hobbyists will also utilize some peat moss in their filters to both help lower the pH and increase the stain to what we often call a “blackwater” display. Blackwater as a term is a little dramatic. The water won't be black, but it will have a substantial color to it that gives the tank kind of a mystical appearance. The lighting in these displays is also dim because it's hard to illuminate water stained this way, and because it enhances the cryptic nature of the aesthetic.

Additionally, these fish can be kept in planted aquariums as they are no risk to the plants, and will appreciate the cover, but the exact water quality they like isn't necessarily great growing conditions. If you want them in a planted display, it makes more sense to choose the aquacultured specimens that were raised in water much more like what they will encounter in your planted tank. If you're going for the blackwater setup, you're free to choose either wild or cultured individuals. Regardless of the look you go for, try to make sure that the substrate is soft, and the décor is smooth, as Hemigrammus rodwayi can be prone to skin infections if they get injuries.

As referenced, this is a very shy fish that would be easily bullied, so careful choices must be made for tank mates. They are good with other tetras from the same genus (Hemigrammus) and Hyphessobrycon. They could also be kept with Corydoras, or small Plecos. They would also be ok in aquariums that house a wider community with small Loaches, Rasboras, perhaps even dwarf Apistogramma Cichlids.

These best display for Hemigrammus rodwayi is one with lots more Gold / Brass Tetras, which naturally leads to the possibility of breeding them in the home aquarium. While not as easy as Guppies or Mollies these fish will breed if given an appropriate environment and a good distribution of males and females. Females will be slightly more round in shape, where males will have more red pigment in the tail coloration and a thin line of white on the front side of their anal fin. Mature fish can be brought into breeding condition through feeding high protein foods like bloodworms and live foods like brine shrimp.

If you are looking to actually rear the fry, a breeding tank is pretty much a requisite as Gold Tetras will eat both the eggs and the fry. This can be done by using a screen over the bottom of the tank that allows the eggs to pass through but prevents the adult fish from getting down to them. Or, alternatively, the adults can be removed from the breeding tank when you see eggs. They will often spawn at night so keep a close eye on them when you suspect spawning is imminent. Lighting should be dim in the tank throughout this process and filtration should be very light. A small sponge filter is all that is needed.

The eggs will hatch in a day(ish), and the fry will be swimming around a few days later. Fry are very small and will need to be infusoria sized foods initially (see our article on homegrown food – infusoria). If you keep these fish in a mature display with some leaf litter, this will generate some natural food all on its own, totally appropriate for the fry being raised there. In a week or so, you can start to feed them baby brine shrimp (nauplii), available from anyone who carries Nutramar live foods (Artemia Nauplii).

Feeding the Gold / Brass Tetras is easy as they usually easily accept both frozen and pelletized foods. Here they get Nutramar's 1.7mm Freshwater Complete pellets, as well as a mix of Mysis, Brine, and Daphnia from Gamma Foods. They will relish the opportunity for live foods like brine and tubifex, but don't really require them unless you are attempting to trigger spawning activity.

The Gold / Brass Tetra is an amazing fish, and certainly a perfect option for people looking for an uncommon tetra to add to their blackwater, or peaceful community display. They are gorgeous, whether cultured or wild, and are easy to feed. If this sounds like a fish you'd be interested in, head to your Local Fish Store and ask them about getting you some aquacultured or sustainably wild harvested Hemigrammus rodwayi today!