Snails from Sulawesi

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The Tylomelania snails are beautiful, inquisitive, lively and adaptable — in fact almost everything you don't generally associate with aquarium snails. Chris Lukhaup explains why they are truly exceptional.

The Tylomelania snails from Sulawesi surprise us all with their colours, patterns and forms. Their size is another factor that makes them without equal in our aquariums. Those colours range from orange to gold-dotted and they proudly show them off if left in relative peace.

During the last few years, the genus Brotia, with their well-known representative, the Brotia pagodula, was a sensation in aquatics. However, it was soon discovered that most imported species do not do well in captivity.

Yet the Sulawesi snails do. If kept at suitable temperatures of 27-30°C/81-86°F, they are the largest imported water snail compatible with tank keeping. They even reproduce in the aquarium.

Stunning appearance

Their appearance is very variable, but always stunning. There are many varieties, from relatively smooth shell structures to heavily-sculptured long, conical shells. Most species have not been scientifically described so far, but many are already offered in the trade.

The shells grow to 2cm-12cm/0.8-4.7“ in length, so some could rightfully be called gigantic. Their apices are almost always corroded. They all have a trap door (operculum) with a central nucleolus surrounded by five to 11 rings. However, the operculum is too small to close off the shell entirely.

The bodies and feet display truly a feast of colour. Some have black bodies strewn with white or yellow dots. Some are monochrome, yellow or orange, or pitch black with yellow tentacles — but all of them look truly stunning.

Their eyes, at the bases of the straight, thin tentacles, are clearly set off against the long, soft, almost cuddly snout.

There is a clearly visible groove, starting in the shell and running over the body and foot, within which the eggs are transported to the outside when they are released.

Range and habitat

Sulawesi (formerly Celebes) near Borneo has an uncommon form. Due to this and its location the island has different climatic zones. The height of the rainy season lasts from late November to March. The mountain ranges, up to 3,500m/11,400’, are mostly covered with tropical forests. Narrow flatlands are close to the coasts.

The height of the dry season is July/August. In the lowlands and on the coasts temperatures are always between 28-32°C/82-90°F. During the wet season, temperatures fall by about two degrees Celsius.

In the Lake Malili system, Lake Poso and their affluents, Tylomelania snails are found on hard as well as soft substrates. The largest population densities have been observed in depths of 1-2m/3.2-6.6’ and their numbers decrease sharply in deeper regions.

On Sulawesi, at the species locations of the snails imported to Europe, temperatures between 26-30°C/79-86°F prevail all year round and the water is similarly warm. Temperatures of 27°C/81°F are still measured at a depth of 20m/66’ in Lake Matano.

The snails described here originate from Lake Poso and the Lake Malili system. Poso is situated at 500m/1,640’ and Matano at 400m/1,312’. Both are in Central Sulawesi. The water is soft and the pH values are between 7.5 (Poso) and 8.5 (Matano).

To provide the snails with appropriate water parameters, the hobbyist snailkeeper should make sure the water is soft and pH high. However, some enthusiasts keep them in medium hard water, although it is not yet known whether this shortens their lifespan or not.

What to feed

Shortly after being introduced into the aquarium and adapting to water parameters, the Tylomelania snails start looking for food. They are not picky eaters and accept additional food.

They eat Spirulina powder, herbivore food, food tablets with a high percentage of animal proteins, and vegetables like cucumbers, bell peppers and courgettes.

Snails originally living on hard substrates will accept vegetables sooner than the others and also like to chew on intact aquatic plants.

When actively looking for food they dig into the ground and hard substrate-dwelling snails will rest on filter mats and decoration placed in the tank.

Reproduction

Of course, we‘d like these snails to reproduce and they have proved to be able to do so in captivity.

As front-gilled snails they are dioecious, the male fecundating the female by passing a spermatophore. This is a lump of spermatozoa held together by cement liquids produced by glandular appendages of the sexual organs.

The offspring grow in eggs in the mother’s brood pouch; each embryo lying in its own section and feeding on the nourishing substance there.

When the embryo‘s development is sufficiently advanced it is transported to the outside from under the mother snail‘s shell lip in a white-ish egg. Within a few seconds the white substance covering the juvenile dissolves and a fully developed youngster emerges.

The egg is transported to the outside in a groove in the mother snail‘s right side. Depending on the species, the juvenile snail is 0.28-1.75cm/0.1-0.7“ long.

When the snail has recently been introduced to an aquarium, so-called shock births happen frequently, possibly caused by differences in the water parameters — so snailkeepers are able to watch these births live shortly after putting the snail into their tanks.

The juveniles born inside their eggs are often a little smaller than usual. However, they can survive — but under normal circumstances they would just have remained inside the mother snail‘s brood pouch a little longer.

Generally, larger species release larger and less juveniles than the smaller Tylomelania.

These snails do not produce a massive population, as they usually release just one young at a time at intervals, and these juveniles need a long time to grow from only a few millimetres to a respectable size.

Aquarium behaviour

After being slowly introduced into the tank, these snails regain their activity pretty soon and go discovering. Only older adults remain in one place for a few days before they start to wander and they don’t change this behaviour pattern later on.

Only when powdered food is fed do they start crawling actively around in order to ingest it!

Many snailkeepers are disappointed with this sedate behaviour. However, if you adapt feeding habits and start giving powdered food several times a day as well as vegetables, you will observe the adults coming out of their shells, too.

For almost all Tylomelania snails taken from nature it soon becomes clear that they do not like their tanks too bright. Sure signs of excessive light are if the snails are jumpy and retreat to darker corners. If you offer them hideaways, in the form of crevices or dense foliage, they will make use of them.

Juveniles hatched in the aquarium are not secretive. They soon get used to the light and crawl freely through the tank. They are agile and eagerly go exploring — going everywhere, regardless whether hard-substrate or soft-substrate dwellers.

However, juvenile snails living on hard substrates can also be found on rocks, plants and wood and so enable us to see them more often.

When stocking a Tylomelania tank, be careful which animals you combine. There are hybrids in nature and different species have been proven to crossbreed in the aquarium, too.

Whether these crossbreeds are fertile is still uncertain. If a true-breeding strain is important, you should refrain from socialising several Tylomelania species.

Home comforts

Most Tylomelania species do well in a 60 or 80cm/24 or 31“ long tank. It should be clear to every snailkeeper that a species that can grow to 11cm/ 4.3“ rather belongs in a 80cm/31” tank, whereas those that reach a maximum 3-4cm/1.2-1.6“ can be kept in a smaller one.

Temperatures should be between 27-30°C/81-86°F and seasonal fluctuations might be sensible.

The snails also need enough room to move, so extremely dense vegetation is rather counterproductive.

Generally Tylomelania snails do well in the company of dwarf shrimp, small catfish and unobtrusive fish. It is important not to co-house them with any large populations of food competitors, so enabling them to find enough at all times.

Substrate should consist of mud, loam or fine sand and having larger rocks is recommended so that snails living on soft substrate as well as those hard substrate dwellers always find what they require.

A good tank decoration should include stacks of stone slabs creating shadows into which the snails can retreat, as they like to do.

These snails are best kept in a dedicated tank, possibly together with some Sulawesi shrimp, for which the water parameters are also appropriate.

An overstocked tank will take all the joy out of watching these beautiful snails, so gather all the necessary information on which snail you want beforehand and house it according to its requirements.

Don’t forget that the amount of food these snails need bears no relationship to what is eaten by those we usually kept in our tanks — Bladder snail, Trumpet snail and so on. They must get extra food, even in community tanks.

These are from an enchanting genus truly coming into their own when kept in a low-stocked tank. For a technical reference, if looking for details on these snails you’ll need to know their taxonomy, note the class is Caeogastropoda; order is Cerithioidea; family is Pachychilidae, and the genus Tylomelania.

Thanks...

To Thomas von Rintelen, of the Humboldt University of Berlin, who has provided me with an insight into these snails and made text documents of the respective scientific works available.

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