The jewels of Sulawesi

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There are shrimps, and then there are demanding shrimps. Gabor Horvath takes the plunge with some of the trickiest freshwater offerings around.

It’s always encouraging to see more and more aquatic shops catering for the needs of shrimp keepers. Nowadays you can find a whole range of specialist soils, decoration and equipment tailored to them. Their popularity isn’t surprising. They’re adaptable, relatively easy to keep and breed, colourful and perfect candidates for nano tanks, bringing the aquatic world close to even those with only limited space available. 

The availability of stock is astounding. There are the bulletproof species (like Cherry shrimp, Neocaridina) for absolute beginners and more challenging ones (like the Crystal Red shrimp and Taiwan Bees, Caridina cantonensis) for more advanced keepers. But what if the colourful palette of the Cherry Shrimp varieties or the intricate patterns of the various TaiTibees don’t satisfy your needs or you want new challenges? Well, that’s when the shrimp species from Sulawesi (formerly Celebes) enter the picture.

Sulawesi selection

Seasoned aquarists are likely familiar with the name of Celebes and will know the fantastic fish hailing from this Indonesian island — species such as Celebes Rainbow, Marosetherina ladigesi, and Celebes Halfbeak, Nomorhamphus liemi, just
to name a couple. 

Sulawesi also has its share of lesser-known secrets: the deep ancient lakes hiding among the highlands of the island. Lake Poso and the Malili Lakes (consisting of five smaller lakes – Towuti, Matano, Mahalona, Masapi, Lontoa) each have a very specific fauna including
a variety of gastropods and crustaceans that you can’t find anywhere else in the world. 

Due to the position of the lakes, only small amounts of organic matter get into them, and their inhabitants had to adapt to the oligotrophic environment. Food can be scant in these lakes. Being mainly diatom, detritus and algae eaters feeding Sulawesi shrimps can cause some problems, something I’ll return to.

Within the lakes there are niche habitats with their unique fauna.

You will find bare sandy bottoms, leaf-and-wood littered areas, macrophyte zones as well as hard rock territories. Certain shrimp species can only be found in one particular microhabitat, while others have a wide distribution across several zones.

What all common in every area is the water temperature. It’s over 27°C near to the surface and similarly 27°C even close to the bottom of the often extremely deep (590m) lakes. This means that the Sulawesi shrimps and snails require much higher than the usual temperatures. 

Water chemistry-wise these lakes have curious parameters. They’re relatively soft (4-8°GH, 3-5°KH), yet quite alkaline at 8.5pH, diverging from the usual ‘soft and acidic’ or ‘hard and alkaline’ trends. It’s the carbonate and bicarbonate content that regulate acidity, so creating and maintaining a proper Sulawesi environment with low carbonate hardness could be challenging. 

Those who have never seen a Sulawesi shrimp may ask, if there are so many difficulties then why bother? My answer is simple: they’re special and bring colours that you only usually see among marine species. 

Sulawesi shrimps all belong to the Caridina genus, like many of our favourite species, such as the Amano shrimp, Caridina multidentata. However, unlike this species the Sulawesi species are fully adapted to a freshwater environment, so they produce well-developed offspring that don’t require saltwater to survive. This possibility of home-breeding just adds to the appeal of these little eye-catchers.

Cardinal shrimps are highly desired but equally demanding.

A cold start

Having kept and bred ‘ordinary’ shrimp species for over a decade I decided to take the plunge and dive into the world of Sulawesi. I set up a tank for a small group of Cardinal shrimp, Caridina dennerli, and then — despite of my best efforts — all but one of them died within a week. The one remaining shrimp was a female carrying eggs, so I hoped the best. Unfortunately, out of the around 12 eggs only two hatched, but even those disappeared within a week. The female lasted for a few months. 

After this failure I reviewed the potential reasons. The first mistake I committed was to get the shrimp during the winter months. When they arrived, the water they were in was below 20°C despite the presence of a heat pack. That’s way too low for such a warmth-lover, and it’s possible that even that brief chill can cause severe harm. Discussing my experience with other Sulawesi shrimp keepers they concurred, many of them reporting similar issues. Cooling down seems to affect wild-caught specimens to a greater extent, and the stress of being caught and then transported to the other side of the world weakens their immune system more. Add a few days starvation prior to and during transit and you can see why they arrive in poor condition.

Furthermore, unless you can meet all of their requirements on arrival, around 90% loss could be expected. Among these needs the most important is — after the correct water parameters — the abundance of diatoms and algae. Although after some time they could get used to artificial foods like Spirulina powder, initially they will only survive by grazing on the aquarium’s biofilm. 

Properly preparing and ageing a Sulawesi tank is essential for their survival. I don’t mean a typical shrimp-tank maturing time of couple of weeks; you may need a much longer period to ensure that the aquarium is ready. My second mistake was to think along the traditional shrimp-keeping lines and to introduce my Cardinal shrimp too early without ensuring enough aufwuchs for them to graze on.
Being a successful shrimp breeder otherwise, this disheartened me so much that I gave up on Sulawesi shrimp for a while.

That was until my friend Tien Dat from shrimpcorner.co.uk asked me if I wanted to try my hand at them again. This time I had an advance warning as the shipment was due in two months’ time, so I could prepare for their reception.

Yellow Cheek shrimps are sensitive.

Setting up right

The first thing I needed was an appropriate aquarium. As Sulawesi shrimps are quite small in theory you could keep them in nano tanks (15 litres upwards), but an experienced friend suggested that they survive better in larger groups, so I wanted something bigger. I came across the product catalogue of a new brand coming to the UK market and I saw the exact kit I needed there. As I planned to write a review on them anyway, after a quick discussion with the distributor of AMTRA products, a shrimp tank and the accessories were on their way. 

My idea was to recreate a rocky bottom habitat, so they also supplied a box of lava stones. These are perfect for such a project, as they don’t leach out any harmful chemicals and provide excellent living space for both aerobic and anaerobic bacteria. The rugged surface is optimal for biofilm and algae growth. 

I opted for an AMTRA Nanotank
60 and began preparing. I started by sprinkling a generous dose of montmorillonite all over the bottom of the tank. This provides useful minerals to the shrimp and is used by many shrimp keepers. You can buy branded products but I bought a bag of cosmetic grade minerals from eBay for the fraction of the price. I’ve used the same supplier for several years now I have never had any problems with it. 

As a substrate I added a layer of JBL Volcano Mineral soil. Traditional shrimp soils mustn’t be used in a Sulawesi tank, as they lower the pH, but inert substrates (sand or fine gravel) are perfectly suitable. I created a rocky landscape from the lava rocks and a few pieces of bogwood. Before using the lava rocks, I soaked them in a bucket of water for a couple of days then placed them into established aquariums with significant algae growth to seed them with both bacteria and algae. Once covered they were moved to the shrimp tank.

I filled the tank with treated and aged tapwater (pH7.4, 5°GH, 2°KH). A GH+ shrimp mineral was used to slightly increase the general hardness (to 7°GH) and sodium-bicarbonate (baking soda) to increase KH and pH. Based on my experience 1ml of sodium-bicarbonate added to 30 litres of water increases the KH by one degree. It also increased the pH, which was 8.4pH after the water settled, making it perfect for Sulawesi shrimps. 

If your water is hard, you should use RO (reverse osmosis) water, adding a special Sulawesi salt available from a few manufacturers. My recommendation is to go with the 8.5 salt, as it seems to work better than the 7.5, though it may take much longer to dissolve, adding some extra days to the preparation. 

Algae growth needs to be seeded in advance.

To keep the water in pristine condition I added two filters to the tank. One of them was a mature air-driven double sponge filter, which I believe is the best way to filter a shrimp tank, as it provides good non-turbulent filtration as well as a large surface for the shrimps to graze on. The other filter was an AMTRA Filpo Click internal power filter, with a removable pre-filter. It seems to be shrimp-safe as well, as the pre-filter cartridge has small pores so the baby shrimp can’t get through it. To kickstart the aquarium I dosed Prodibio Biodigest Bacteria and Stop Ammo. As Sulawesi tanks run at a relatively high temperature, a reliable heater is essential. I used an AMTRA Klima Evo heater that fits the bill perfectly, holding 27-28°C with only negligible fluctuation. 

As you’ll no doubt know, growing algae is easy when you don’t want it, but when you need the stuff it never grows. I did my best to provide my greens with everything they need to flourish, including adding Prodibio Biovert Plus plant food (being careful not to overdose) and using an AMTRA Vega LED light. For the first two weeks the light was on for 18 hours a day, so the tank quickly turned green and the decoration was covered by fluffy algae growth. I reduced the lighting to 12 hours and began removing the excess. If you have issues with filamentous algae, try my method. 

Find a wooden skewer (the cheaper and rougher is the better) and rotate it while touching the algae filament. The stick will pick the thread up and clear the algae away, pulling it off from your decoration or plants. After lifting the stick out simply pull off the algae and repeat the process. 

A gorgeous Sulawesi Harlequin shrimp.

Snail control and stocking

It wasn’t only algae that appeared. From the bogwood a bunch of tiny snails got into the tank and within days they began to proliferate, cleaning the algae from the rocks.
I needed to take drastic measures,
so moved two of my Pygmy puffers, Carinotetraodon travancoricus, to the tank. I was worried about the high pH but they weren’t affected at all and cleared up the snails in no time, so I left them in the Sulawesi tank until the day before the shrimp’s arrival to keep the nitrogen cycle ticking over. 

When the courier arrived, I sprung into action and after the usual acclimatisation (dripping aquarium water to their container, so they could get slowly used to the new parameters) the new arrivals were introduced to the tank.

 I received three species: Cardinal shrimp, Caridina dennerli, Sulawesi harlequin shrimp, Caridina woltereckae, and Yellow-cheek shrimp, Caridina spinata. Although they’re not found together in the wild (C. dennerli is from Lake Matano, while the other two are from Lake Towuti) they have similar requirements. As far as I’m aware they can be kept together, with no reliable reports (there are only rumours) of crossbreeding between various species. 

Those familiar with other ornamental shrimp will be disappointed with the skittish nature of Sulawesi species. Unless kept in larger numbers they will spend most of their time hiding and even when they’re out you can expect them to dart back to the nearest crevice at any moment. It makes photographing them a very challenging task. Tank bred specimens are braver and it’s comical to watch the white-socked Cardinal shrimp move around, picking up morsels of food looking like they’re dancing. 

The Yellow Cheek has a distinct appearance.

Out of the three species I have the Cardinal shrimp is the easiest one to keep (and the most frequently available), so if you’re planning to plunge then that’s the one to start with. Sulawesi Harlequin shrimp (not to be mistaken for the marine Harlequin shrimp, Hymenocera picta) are the smallest of the lot, barely reaching 20mm. But what they lack in size they make up for in appearance: the intricate red pattern is eye catching and especially striking when they’re contrasted against green algae covered rocks. 

The most difficult of the lot is the Yellow-cheek — even the most experienced shrimpkeepers struggle to keep them alive, let alone breed them. It could be that they require a special, but presently unknown element in their diet. 

If Sulawesi shrimp survive their first two weeks after transport (in my case due to the careful preparation the mortality was ‘only’ 20%) there should be no significant losses. Beside maintaining a healthy biofilm (dosing extra bacteria may be necessary) and vibrant algae layer you can try to feed them small amounts of powdered foods (such as Spirulina or fry food), but make sure not to overfeed them. 

The Sulawesi Harlequin can rival marine shrimps for markings.

To clear up the leftover food you could use snails from Sulawesi (Tylomelania), which will also add some interest to the tank. Be careful during water changes, as every Sulawesi shrimp is sensitive to sudden water parameter changes. Using a drip method of gradually trickling replacement water back in to the tank could save many lives. 

Before getting into Sulawesi shrimp keeping consider well whether you could commit yourself to their demanding needs, and if you would be content to accept the financial loss (and moral, with the loss of lives) which may occur. If you have never kept any shrimp before they’re definitely not for you. Only after keeping and breeding shrimp for many years and fully understanding the differences between the needs of crustaceans and fish, plus having the full knowledge of maintaining non-regular water parameters should you attempt to keep them. Until then you should just watch the YouTube videos about Sulawesi and imagine swimming in those lakes. I still do it, and often too.