Alex Bell takes a look at a charming, small marine fish that happily lives in loose shoals: the chalk bass (Serranus tortugarum).
The reef hobby is dominated by aquariums housing a wide variety of species, many of which are kept individually. When people ask for a shoaling fish suitable for reef tanks, the usual response will either be green chromis (Chromis viridis) or a species of anthias. Some may go as far as suggesting a species of cardinalfish as well.
However, there is one beautiful fish that is all too often overlooked. The chalk bass (Serranus tortugarum). This species lives in large groups in the wild, and even in the confines of an aquarium it rarely shows territorial aggression to conspecifics. So what are they, how do we keep them, and why are they overlooked?
The Chalk Bass Lowdown
There are two common names that Serranus tortugarum is frequently known by: the chalk bass and the Caribbean blue bass. The latter gives us some indication of where this fish naturally occurs, and you will likely see both names used in the UK hobby.
Hailing from the Western Atlantic, the chalk bass can be found from southern Florida down through the Caribbean to the northern coast of South America. Here they typically live in large shoals above areas of coral rubble and sandy substrates that sit alongside coral reefs.
All images by Shutterstock unless otherwise stated
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Chalk Bass Fact File
Scientific name: Serranus tortugarum
Size: up to 8cm (3.1”)
Origin: Western Tropical Atlantic
Habitat: Coral rubble and sandy substrates alongside reefs.
Tank size: 80x40x40cm (31x16x16").
Temperament: Peaceful, gregarious, and generally reef safe, although they will eat small ornamental shrimp.
Feeding: Generally unfussy, eating most live, frozen and dry foods. Feed multiple times a day to replicate their natural feeding habits.
Availability & cost: Uncommon in shops, expect to pay roughly £25 per fish.
Natural Diet and Feeding
Chalk bass spend their days in the tropical Atlantic snatching drifting zooplankton from the water column. They are constantly on the move, swimming against the strong currents that carry their food. They also have high metabolisms, which makes them rather ravenous reef inhabitants.
Much like anthias, multiple small feedings a day will be needed to keep them well fed, although they are far less demanding of this. Being carnivores – preying on small shrimps, larval fish, and other tiny zooplankton – they are well suited to many of the common aquarium foods. Mysis, brine shrimp, lobster eggs, chopped krill and various granules and flakes will all be taken readily once the bass are settled.
Photo by Alex Bell
Tank Size and Setup
The size of the aquarium will be determined by the number of individuals you keep. With a maximum size of 8cm (3.1"), a lone chalk bass would be suitable in aquariums holding 125 litres (27 gal/33 US gal) or more. However, they are social animals that form loose shoals, and replicating this behaviour allows aquarists to observe more natural and entertaining interactions.
Larger aquariums will be required for housing a group, and you'll want to aim for five or more individuals – added simultaneously to reduce the risk of any aggression. Allow for at least 50 litres (11 gal/13 US gal) per chalk bass, although more space is always better.
While these fish may spend a lot of time feeding in the open on the reefs, they never stray too far from cover. Including plenty of rockwork with crevices and overhangs will help your chalk bass feel safe and secure, meaning you'll see them more.
One other thing to consider when setting up an aquarium for this beautiful fish is that they are keen jumpers, so a jump net must be fitted to any open topped reef tanks.
Behaviour and Compatibility
The chalk bass is almost a model reef inhabitant. They are completely safe with all corals, so feel free to cover the rocks in LPS, SPS and softies. However, caution should be taken when adding any small ornamental shrimp to the tank. Small shrimp that can fit in a chalk bass's mouth will likely be predated on, so definitely no sexy shrimps.
They are also fairly peaceful towards other fish. The problem is usually with overtly aggressive species picking on the chalk bass. Avoid highly territorial dottybacks and damselfish (like the humbug damsel pictured above), as well as anything large and predatory that may see them as food.
Related article: Back to saltwater: starting simple with beginner corals.
Perfect Tank Mates
There are plenty of suitable tank mates for your chalk bass available in the marine hobby. Below is a short list of some of the common options:
- Common clownfish
- Firefish
- Cardinalfish
- Gobies
- Blennies
- Small wrasses
Did You Know?
One of the most remarkable things about the chalk bass may not be that obvious to a reef hobbyist. They are simultaneous hermaphrodites, meaning each fish possesses both male and female reproductive organs at the same time.
They are unable to self fertilise, but pairs engage in "egg parceling", where they alternate male and female roles when spawning.
Why Are Chalk Bass Not More Popular?
Fishkeepers are often attracted to the marine hobby due to the vibrant colours of both the fish and corals. Unsettled and newly imported juvenile chalk bass aren't the most vibrant fish, and are easily overlooked at your local marine store in favour of more garish but sensitive options like anthias.
However, given time this species is anything but a chalky white fish. Instead they sport a lilac-blue underside alongside a contrasting reddish brown and iridescent blue striped pattern on the dorsal side. They are certainly an attractive species, plus their care requirements are far less daunting.
Another reason for their lack of popularity may simply be their common name, "chalk bass". Unlike names like "flame angelfish", "royal gramma" and "peacock wrasse", it doesn't exactly scream iridescent colours, tropical seas, and thriving reefs.
They may not be appear in stores that often, but ask and they should be able to source them for you fairly easily. Indeed, many years ago when I was in the trade we went through a period of ordering more every week, reefers loved them once they had seen them in the flesh!
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An Underrated Reef Gem
Despite their understated name, chalk bass are an incredibly rewarding species. Hardy, peaceful, reef safe, and naturally social, they offer all the movement and personality of more demanding shoaling species without the same level of difficulty. Given the right setup and a little time to settle in, a group of chalk bass can become one of the most engaging and attractive inhabitants in a reef aquarium.