Zodiac Or Batik?

There is cool little loach called Koitha in its native range, which is west flowing streams in western and southern India, where it is very common. You'll know it better as either the Zodiac Loach, or the Batik Loach; the names that it has among English speaking aquarium keepers. To avoid any further confusion, it scientific name (binomial nomenclature) is Nemacheilus triangularis. It is a small fish, rarely getting much bigger than two inches long.

The Zodiac Loach comes from the upper ranges of clear, fast-moving streams where it is usually found in groups. They are a naturally social animal, and we suggest keeping them as such in your aquarium. We recommend keeping a minimum of five, and if this is not possible, attempting them as a single specimen may be a better choice. Keeping less than five doesn't distribute their normal pester some behavior enough, and the individual fish could suffer.

When planning a display for the Zodiac Loach, some thought should be put into their native environment. They come from areas that are flowing, cool and clear, and thus the water is very oxygenated. We recommend using high flow filtration like canisters, aiming for at least 20 times the volume of the aquarium in filter flow. If you have a group of these in a 40-gallon tank (conveniently our minimum recommended size for our group of five to nine) you should be running a canister filter that pushes 200 gallons per hour. Substrate should be big enough not to get blown around, and riverine in appearance. Large, rounded rock, like the White Water and Desert Storm series from Ecoscape would be excellent choices and can be seen here: https://www.qualitymarine.com/ecoscape/monument-rock-series/ To add interest, environments could also be filled in with smooth driftwood (also available from Aquatropic Partners who carry the Ecoscape line.)

In regard to water quality, outside of dissolved oxygen, Nemacheilus triangularis is a straightforward fish to keep. They like temperatures in the low 70s, as cooler temperatures help the water hold more oxygen. They'll be fine down to the mid 60s, and up into the 77-78 range, though you shouldn't go higher than this. A neutral to slightly acidic condition is the norm and aiming for 6.5-7.5 will be fine. We don't find them to be overly sensitive to hardness. The one caveat here is that these fish are somewhat intolerant of dissolved nutrients, and so a close eye should be kept on nitrogen-based waste. Regular water changes and gravel vacuuming, in conjunction with the oversized filtration you're already running should conquer any challenges you have with organic waste.

In its wild environment, Nemacheilus triangularis primarily eats aquatic invertebrates and as such is pretty unlikely to bother decorative plants in your aquarium, but the faster flowing conditions that these fish prefer is not conducive to growing them. If your intent is to have these fish in your planted aquarium, you'll need to increase the dissolved oxygen levels by utilizing air stones (which then could be at odds with your carbon dioxide dosing.) Point being, Zodiac Loaches can work in planted tanks, though there are some challenges. In larger aquariums, these challenges get easier to mitigate.

The wild diet of the Zodiac Loach is high in protein, and this should be emulated in the home aquarium. We find that they are fairly amenable to taking a sinking pellet, and we mix this with other high protein foods like mysis, gut loaded brine, bloodworms, tubifex etc, and they take all these foods with gusto. They are so active, and like so much flow, that they should be fed twice a day. A varied diet like the one we described will keep them in their best condition. In house they get the Freshwater Complete pellet from Nutramar foods, and a mix of frozen offerings from Gamma Foods including those listed earlier.

Nemacheilus triangularis is a relatively peaceful, but active and pesky fish. They primarily live on or near the bottom and so we don't recommend keeping them with bottom dwellers that are very sedate and peaceful. Avoid things like Starry Borneo Suckers and Corydoras, especially dwarf varieties. Better tankmates would include fish that are robust, faster swimming fish that live in the middle and upper parts of the water column: Barbs, Danios, larger Tetras etc. We've seen some displays where Panda Garras and Siamese Algae eaters are also working well groups of Zodiac Loaches. You should avoid keeping them with invertebrates as these will be seen as food.

This fish has been bred in captivity, and there are many citations of a single event where this was well documented. There are other scattered reports of hobby aquarists accomplishing this, both intentionally and unintentionally. Nemacheilus triangularis are not regularly available as aquacultured specimens yet, and so the challenge of reliably replicating this captive breeding (especially on a commercial level) awaits a dedicated aquarist somewhere! We recommend starting with water in the low-mid 70's, feeding well, and removing fish from larger groups when they establish pairs to move them into more private quarters. Eggs are reportedly clear, and non-adhesive, so filtration will need to be adjusted so as not to suck eggs up. Parent fish will likely consume the eggs and need to be removed after spawning events. Fry will need tiny food initially, like infusioria (culturing tiny foods for tiny fry article coming soon). Good Luck!

Nemacheilus triangularis is a beautiful fish with markings that grow more intricate and distinct as they age. There are some reports out there of individual Zodiac Loaches that get aggressive, though we haven't experienced that here. It's always possible that an individual fish is a miscreant, however, it may also be that those fish are either misidentified, being kept singly in peaceful community tanks, or possibly being kept in lower flow aquariums, all of which could trigger the kind of problematic behavior being described. This is a wonderful fish for a tropical river type display, and groups of them are endlessly fascinating to watch. If you're interested in them, and you should be, head to your Local Fish Store and ask about getting you a bunch of sustainably sourced Zodiac Loaches from Aquatropic today!