92 Marine Molluscs, Crabs And Shrimps Care Sheet Molluscs

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How to care for...

Marine

molluscs, crabs

& shrimps

92 Tropical marine invertebrates

If in doubt contact

your OATA

retail member

for further

information

Scan this code to

download an

electronic copy

© Copyright OATA Ltd 2010 May 2013

Important things to remember

Always buy...

test kits and regularly check the water for ammonia, nitrite,

nitrate and pH. This will allow you to make sure the water in

your aquarium is not causing welfare problems for your fish.

Establish a routine...

for testing the water in your aquarium. Record your results

to enable you to highlight fluctuations quickly. Also check

the temperature of the water.

Maintain...

the water in the aquarium within the accepted parameters

highlighted in this leaflet. You may need to do regular water

changes to achieve this.

Always wash your hands...

making sure to rinse off all soap residues, before putting

them into your aquarium. Wash your hands again afterwards

and certainly before eating, drinking or smoking.

Never siphon by mouth...

A fish tank can harbour bacteria which can be harmful if

swallowed. Buy a specially designed aquarium gravel cleaner

which can be started without the need to place the siphon in

your mouth.

Never release your aquarium

animals or plants into the wild

Never release an animal or plant bought for a home

aquarium into the wild. It is illegal and for most fish species

this will lead to an untimely and possibly lingering death

because they are not native to this country. Any animals or

plants that do survive might be harmful to the environment.

Before purchase make sure that:

You have the appropriate equipment and position for

the aquarium.

You have researched all the species you are interested

in and your final choices are all compatible.

You are familiar with how to transport and release

your fish.

You are aware of the daily, weekly and monthly

maintenance your aquarium will require.

You are prepared to look after your fish properly for

the duration of their life.

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Checklist

Glass or plastic aquarium

Gravel cleaner

Water testing kit

Marine salt

Marine substrate & live rock

Filter & protein skimmer

Food

Heater, thermometer & hydrometer

Reverse osmosis/de-ionised water or tap water

conditioner

Before purchase make sure:

The water parameters are as advised

The aquarium is well-established

The species you choose is compatible with your set-up

Equipment

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Introduction

Maintenance

Feeding

Water requirements

Potential problems

Aquarium requirements

As with all marine animals this group of organisms will not

tolerate poor water quality. The water is recommended to be

kept within the following parameters, although these animals

may acclimatise to different water over time:

Temperature: 23 to 26°C

Ammonia: 0mg/l (0.01mg/l may be tolerated for short periods)

Nitrite: 0mg/l (0.125mg/l may be tolerated for short periods)

pH: 8.1 to 8.4

S.G: 1.020 to 1.025 at 20 to 25°C

Marine invertebrates can add a fascinating focal point to a

marine aquarium. They can also make up the ‘clean-up crew’,

eating detritus, algae and some pests such as Aiptasia and

bristleworm.

This diverse group of animals includes shrimps, crabs, snails

and sea slugs have similar requirements, but always check with

books and your retailer to their precise needs.

Most of these animals are scavengers or algae eaters. Therefore,

the aquarium needs to be well established in order to provide a

food source for them. A large aquarium is more stable than a small

nano aquarium, although these animals have been successfully kept

in both. The tank should have a large area of live rock which allows

plenty of surfaces for algae to grow on and hiding places for these

animals.

The aquarium will require a filter, heater, thermometer,

hydrometer and water testing kit. These are essential to maintain

and monitor water quality, the addition of a protein skimmer will

also be beneficial.

These species do not require any specialised lighting however

marine lighting can bring out the colours of your animals and

promote the growth of organic matter which is used as a food

source.

Some marine fish will feed upon these small invertebrates so it is

important to ensure the organisms are fully compatible with the

animals already kept in the aquarium.

The shrimps and crabs which are readily available are often

scavengers feeding upon food left by fish and detritus at the

bottom of the tank. Arrow crabs are often bought for their

particular liking for bristleworm, but they will also readily

accept aquarium foods.

Algae eating snails will feed upon the algae which builds up in

your aquarium. Other snails can be used to sift the substrate,

such as Nassarius snails which feed upon detritus.

Nudibranchs, although spectacular in colour are not easy for

beginners to look after. Often they are fussy feeders, in some

cases, eating only one species of marine sponge. If considering

keeping these, ask your retailer or consult books to obtain as

much information as possible to ensure you can cater for their

specific needs.

A water quality problem will affect invertebrate behaviour and

can be shown by loss of colour, loss of appetite, erratic

swimming. Immediately test the water if any of these symptoms

are shown. Poor water quality is the main cause of disease

outbreak in aquariums. If in doubt ask your OATA retailer for

advice.

At least every two weeks, a partial water change of 25 to 30% is

strongly recommended (a siphon device is also useful to remove

waste from the gravel). This help to reduce the build-up of

potentially harmful nitrates and other pollutants. Replacement

water should be dechlorinated using strong aeration or a tap water

conditioner (if not using reverse osmosis water). Ideally,

replacement water should be heated and enough salt should be

added to achieve the correct salinity.

Filters should be checked for clogging and blockages. If the filter

needs cleaning, then do not wash it using tap water; any chlorine

present may kill the beneficial bacteria that has established within

the media. Instead, it can be rinsed in tank water which is removed

during a partial water change. This should reduce the number of

bacteria lost.

Good husbandry is essential because these invertebrates can be

sensitive to even the smallest amounts of ammonia and nitrite. Test

the water weekly to monitor ammonia, nitrite and nitrate, especially

after initial set-up and after adding new fish. If keeping hard corals,

monitor calcium levels for healthy growth. Do not forget to check

the salinity as this may increase due to evaporation of water.

These invertebrates are highly sensitive to copper which may be

found in some fish medications. If a medication is required, consult

your OATA retailer to obtain a copper-free medication.

Molluscs are a large groups of soft bodies creatures such as sea

slugs and sea hares, while some may have protective shells such

as snails and cowries. Most species are small but some may

reach up to 10cms.

Shrimps and crabs belong to the arthropods, which means

‘jointed leg’. These hard-bodied creatures possess exoskeletons

that must be shed in order for them to grow. This process,

known as moulting or ecdysis, is often a surprise to first-time

keepers of these creatures as they often mistake the old

exoskeleton for a dead shrimp or crab, only to find the moulted

creature to reappear. Immediately after moulting, the shrimp

or crab will be relatively soft and vulnerable, but its new

exoskeleton will harden up over time.

Hermit crabs lack the hard covering possessed by other crabs.

Instead, they will use shells from other creatures for protection.

These will be upgraded for larger shells as the hemit crab

grows.

Most shrimps and crabs available remain small, with few

exceptions. Some may reach 10 to 15cms, so seek advice

from your OATA retailer before purchase.

Biology

Listed below are some of the more common invertebrates which

can be deemed ‘reef safe’. Please be aware that common names

for some of these creatures can vary enormously:

Shrimps: Camelback, Peppermint, Boxer, Fire, Cleaner,

Anemone.

Crabs: Arrow, Dwarf red/blue/zebra hermit, Sally lightfoot,

Emerald, Red hermit, Anemone.

Snails: Turbo, Trochus, Cowrie, Astrea, Nassarius.

Species that require careful consideration and research include:

Harlequin shrimp: feeds only upon tube feet of echinoderms.

Mantis shrimp: will feed upon all fish species and can cause

injury.

Some nudibranchs: feed upon a single sponge species.

Compatibility

There are few reports of this group of organisms breeding

in home aquaria.

Breeding