Dwarf chain loach, Yasuhikotakia sidthimunki

9a0fa740-cc6b-4be3-b9de-f44ea5123d20

Editor's Picks
Features Post
Rathbun’s tetra in the wild
13 September 2021
Fishkeeping News Post
Report: 2021 BKKS National Koi Show results
13 September 2021
Features Post
The World's forgotten fishes
16 August 2021
Features Post
Black phantoms in the wild!
02 August 2021
Features Post
Understanding territories
06 July 2021

Dwarf chain loach, Yasuhikotakia sidthimunki, are sometimes referred to as 'monkeys' – a name which Emma Turner reckons is very apt for these wonderful little community fish.

If searching for that special something for your mature community tank, take a look at the Dwarf chain loach. With its pretty appearance, outgoing, and inquisitive personality, Yasuhikotakia sidthimunki is the smallest botiid and could be just the character to liven proceedings.

Dwarf chain loaches, or  'monkeys' or 'sids' as they are often known, once occurred in vast numbers in river basins of the Chao Phraya, Kwai and Mae Klong of Cambodia, Laos and Thailand.

Numbers are dwindling however, largely due to hydro-electric damming, and the species is declared 'critically endangered' on the IUCN red list. In Thailand it is now protected.

Thankfully, they have been spawned in captivity on a large scale, via hormone treatment, for the trade and some also naturally, but in smaller numbers, by dedicated hobbyists.

Captive projects in South-East Asia ensure a good supply, but price tags remain high. It is not unusual to pay £7-10 per loach and they must have the company of their own kind, so six specimens should be the absolute minimum. However, this outlay will reward you with much enjoyment.

Being a dwarf species that rarely exceeds 6cm/2.4", Y. sidthimunki is a good choice for smaller aquaria. They do require room to swim though and the length and width of the tank is more important than height. I would not recommend them for any home under 76cm/30" in length.

The aquarium must be mature and have a substrate of soft sand or very fine smooth gravel to protect this fish’s delicate sensory barbels. A myriad of hiding places should be provided among bogwood, slate, rocky caves and robust planting.

Hideaways aplenty

The more refuges you create for them, the more you will see them. They need to know they always have plenty of options for a quick retreat if sensing danger. Once settled in to their surroundings, this knowledge will ensure they spend a lot of time in full view.

The water should be well oxygenated and with moderate to fast current. Many keepers of this species have noted that, when increasing the flow in the tank, their sids welcomed the change and were out playing more often.

Tight-fitting cover slides are a must as, like all loaches, they can and will jump. While delicate plants may be nipped at, species such as Anubias and Java fern (Microsorum sp.) are safe and do not seem to mind the slightly subdued lighting the loaches prefer.

Good filtration, a regular water change regime of approximately 25% per week and a varied diet will keep your sids in tip-top condition. Neutral water is best, but clean, stable conditions are more important than playing around too much with hardness and pH. Temperature should be within 24-28°C/75-82°F.

Unusually for loaches, Y. sidthimunki not only spend time on the bottom of the tank but can often be seen actively shoaling in midwater together, often playing ‘follow my leader’, stopping now and then to hover and excitedly flap their pectoral fins in enjoyment.

This behaviour means they will take food from all levels of the tank— be it flake, pellets, granules, wafers, or small meaty frozen foods.

Keep a large group all together. By this I mean a large group of sids — not a large group of mixed loach species. Not only will they then develop a complex social hierarchy within their own shoal, but their overall behaviour will be more natural.

Happy sids are those that may breed for you and, with only a handful of spawnings reported from the home aquarium, this is something to strive for.

Living in harmony?

With regards to tank mates, consider what should be a good combination. Small fish from the same continent include some of the beautiful Rasboras, such as the Harlequin (Trigonostigma heteromorpha), Narrow wedge harlequin (T. espei) and Microrasbora kubotai.

All these species seem to enjoy areas of current within the tank, and décor can be aquascaped to provide calmer areas, should they decide they’d like to move out of the stronger flow for a time.

Some small barbs and danios would co-habit well, but are much more likely to predate on eggs/fry should you be rewarded with spawning sids. Add a shoal of dither fish to the tank, as their presence will signal that all is well and the coast is clear to come out and play!

Be cautious, however, about keeping sids with slow peaceful bottom-dwelling Corydoras catfish and the like, as ‘the monkeys’ can be too boisterous. They have been known to be so inquisitive as to inflict physical injury on Corydoras, such as biting at their eyes.

I don’t want to seem alarmist, as more often than not there will be no compatibility issues whatsoever. Most of the time, sids are very much model citizens.

The majority of snails however will be seen as a tasty snack, so don’t add sids to a tank of ornamental snails!

Y. sidthimunki can easily be confused with juvenile Y. nigrolineata, the Black lined loach. However, Y. nigrolineata generally attain a much larger adult size and are rarely seen in the trade.

Y. sidthimunki tend to show much more in the way of vertical barring between the dark horizontal stripes, but this should not be totally relied on as there are always exceptions.

Where does it belong?

In 2004, Dr Maurice Kottelat reclassified many of the former Botia group loaches, placing some into newly erected genera. The loach formerly known as Botia sidthimunki is currently referred to as Yasuhikotakia (pronounced yah-soo-high-ko-tay-kee-ah) sidthimunki.

Later research suggested placing the fish in their own family, Botiidae.

Whether or not Y. sidthimunki and Y. nigrolineata really do belong in the Yasuhikotakia genus needs further investigation, as initial studies show these two species are more likely to fit into the Sinibotia genus.

Discovery of giants

Then, to add to confusion, there are reports of the discovery of a population of 10cm/4” Y. sidthimunki type loaches in Nan province in North-eastern Thailand, which are tentatively referred to as Y. cf. nigrolineata on account of the uncertainty of being one or the other.

Although I cannot provide any real proof yet, my Y. sidthimunki must be breeding. Some months back I spotted a small specimen less than one-third of the body length of my mature adults — and no new fish have been added to this tank for years.

Mark Duffill, a fellow loach enthusiast and good friend, has even described the probable spawning behaviour and obtained photographs of the youngsters alongside his breeding adults.

What started off as a large shoal of 36 specimens, soon became 42 under his care. Spawning appeared to follow a series of cool water changes carried out after late summer temperatures had caused the aquarium water temperature to rise higher than normal.

When the water changes were carried out, some dried Indian almond leaves (Terminalia catappa) were added to the tank, which helped to soften the moderately hard water. The pH decreased from 7.6 to 6.8.

The sids became more excited than usual and most, if not all the group, swam together in a tight shoal, repeatedly darting in and out of the bogwood and plants.

Two and a half months on, Mark observed a very small Y. sidthimunki swimming very close to the rocks at the front of the tank. On closer inspection, he spotted two more of the same size, which were about 1.9cm/0.75”. A head count revealed six youngsters in the tank!

I can’t recommend these loaches enough. They are attractive, full of boundless energy and their antics will keep you enthralled. Breeding them is an accomplishment to be proud of. If you have space in the right kind of set-up, give these cheeky little monkeys a go!

This item was first published in the June 2009 issue of Practical Fishkeeping magazine. It may not be reproduced without written permission.