🦞 Blue Lobster Care Guide

Blue Lobsters are striking freshwater crustaceans known for their vivid blue colouring, unusual appearance and fascinating behaviour.

Despite the common pet-shop name “Blue Lobster”, these animals are actually freshwater crayfish rather than true marine lobsters.

They are active, inquisitive animals that spend much of their time exploring, climbing, digging and searching for food.

Depending on the exact species sold as a Blue Lobster, adults can reach approximately 10–15cm or more.

They can live for several years with correct care.

Because different crayfish species can be sold under the name Blue Lobster, always check the exact species where possible, as adult size and requirements can vary.

♂️♀️ How to Tell the Sex

Sexing a Blue Lobster (Electric Blue Crayfish) can be difficult when they are young, but the differences become easier to identify as they grow and mature.

🦞 Males

Mature males generally have:

• Modified swimmerets underneath the body used during mating
• The first pair of swimmerets are more rigid and point forwards
• Reproductive openings located around the base of the rear walking legs
• Often larger, more developed claws, although this isn't a reliable method on its own

🦞 Females

Mature females generally have:

• Softer, more uniform swimmerets underneath the abdomen
• Reproductive openings positioned around the base of the third pair of walking legs
• A broader abdomen, which provides space for carrying eggs
• Swimmerets underneath the abdomen that are used to hold and carry eggs

🔍 Check the Underside

The most reliable differences are found on the underside of the crayfish, rather than judging by colour, size or claw size.

The position of the reproductive openings and the appearance of the swimmerets can help distinguish mature males from females.

Avoid unnecessary handling or turning the crayfish over for prolonged periods simply to determine its sex.

⚠️ Young Blue Lobsters

Young Blue Lobsters can be difficult to sex accurately because their reproductive features may not yet be clearly developed.

Colour should not be used to determine sex — both males and females can develop the striking blue colouration.

⚠️ Sexing Disclaimer

Please note that Roxy’s Pet Shop is unable to guarantee the sex of any livestock.

Where we provide a suggested sex, this is based on the animal’s visible characteristics, age and our experience at the time. Some animals can be particularly difficult to sex when young.

Any sex stated should therefore be treated as our best assessment and not a guarantee.

🏠 Aquarium Size

Blue Lobsters need a spacious, secure and properly filtered freshwater aquarium.

For a single adult, an aquarium of approximately:

80–100 litres or larger

provides a useful starting point, although the exact requirement depends on the species and adult size.

Floor space is particularly important.

The aquarium should provide:

• Good filtration

• Plenty of floor space

• Multiple hiding places

• Caves

• Rocks

• Wood

• Suitable substrate

• Clean, treated water

• Secure lid

• Thermometer

• Areas to explore

Larger is always preferable.

🔒 They Are Escape Artists!

Blue Lobsters are surprisingly good climbers.

They may climb:

• Filter pipes

• Airline tubing

• Decorations

• Plants

• Cables

Any aquarium containing a crayfish should have a secure, well-fitting lid.

Check carefully for gaps around:

• Filters

• Cables

• Pipework

• Feeding hatches

A gap that looks too small may still provide an escape route.

💦 Water Quality

Excellent water quality is essential.

Poor water conditions can cause stress and may create serious problems, particularly around moulting.

The aquarium should be fully cycled before introducing your Blue Lobster.

🔄 Cycling the Aquarium

Beneficial bacteria inside the filter process waste through the nitrogen cycle:

Ammonia → Nitrite → Nitrate

Aim for:

Ammonia: 0 ppm
Nitrite: 0 ppm

Nitrate should be kept under control through sensible stocking, good filtration and regular partial water changes.

Cycling can take several weeks.

Simply filling an aquarium and switching the filter on for a couple of days doesn't mean it is cycled.

🧪 Testing Your Water

Regularly test:

• Ammonia

• Nitrite

• Nitrate

• pH

Stable water conditions are important.

If your Blue Lobster behaves unusually or becomes inactive unexpectedly, checking the water should be one of your first actions.

🚿 Tap Water

Always use an appropriate aquarium water conditioner/dechlorinator when adding tap water.

Chlorine and chloramine can be harmful to aquatic animals and beneficial filter bacteria.

Crustaceans can also be particularly sensitive to certain chemicals and medications.

🌡️ Temperature

For many commonly kept freshwater Blue Lobsters/crayfish, a temperature of approximately:

🌡️ 20–24°C

is a useful general range.

However, requirements vary between species.

Avoid rapid temperature changes and overheating.

Use a thermometer to monitor the aquarium rather than guessing the temperature.

If additional heating is required, protect the heater so the crayfish cannot damage it or become trapped against it.

⚗️ Minerals & Water Hardness

Crayfish need minerals, particularly calcium, to develop and maintain a healthy exoskeleton.

Very soft or mineral-poor water can sometimes contribute to moulting difficulties.

Maintaining appropriate:

• pH

• GH

• KH

• Mineral content

can therefore be important.

Avoid trying to change water chemistry rapidly.

Stable, appropriate conditions are preferable to constantly chasing exact numbers.

🔄 Filtration

Blue Lobsters can be messy feeders and require good filtration.

Suitable filtration may include:

• Internal filters

• External canister filters

• Other appropriately sized aquarium filtration

The filter should provide good:

• Mechanical filtration

• Biological filtration

• Water circulation

Make sure filter intakes and equipment can't trap or injure the animal.

The filter should normally run 24 hours a day.

💨 Oxygenation

Good oxygenation is important.

Surface movement from the filter can help.

Additional aeration can be provided using:

• Air pump

• Air stone

• Bubble bar

This can be particularly useful during warmer weather.

🪨 Substrate

Suitable substrates can include:

• Aquarium sand

• Fine smooth gravel too large or appropriate enough not to cause problems

• Other suitable freshwater aquarium substrates

Blue Lobsters often enjoy:

• Digging

• Moving substrate

• Rearranging their environment

Don't expect your carefully designed aquarium to stay exactly how you arranged it!

🪵 Hiding Places

Hiding places are extremely important.

Provide caves and shelters using suitable:

• Rock caves

• Wood

• Pipes

• Crayfish hides

• Aquarium ornaments

The animal should be able to completely retreat from view.

This is particularly important during moulting, when the crayfish is soft and vulnerable.

🌿 Plants

Blue Lobsters and planted aquariums can be a difficult combination.

They may:

• Dig plants up

• Cut plants

• Eat plants

• Move decorations

• Rearrange substrate

Hardy plants may survive, but don't assume any plant is completely safe.

Artificial aquarium plants can sometimes provide additional cover without becoming an expensive snack!

🧗 Enrichment

Blue Lobsters are active and inquisitive.

An interesting environment can include:

• Caves

• Rocks

• Wood

• Different substrate depths

• Tunnels

• Areas to climb

• Multiple routes around the aquarium

Make sure all heavy decorations are securely positioned.

Because crayfish dig, unstable rocks can potentially collapse.

🍽️ Feeding Your Blue Lobster

Blue Lobsters are omnivorous scavengers.

A varied diet can include:

• Quality sinking crustacean foods

• Sinking pellets

• Algae wafers

• Suitable vegetables

• Appropriate frozen foods

• Occasional suitable protein-rich foods

A varied diet is preferable to feeding one food exclusively.

🥬 Vegetables

Suitable vegetables can include small amounts of:

• Courgette

• Peas

• Spinach

• Green beans

• Other appropriate vegetables

Remove uneaten fresh food before it begins to spoil.

🐟 Protein Foods

Suitable protein-rich foods can be offered as part of a varied diet.

Options may include:

• Appropriate sinking foods

• Suitable frozen aquatic foods

• Specialist crustacean foods

Avoid excessive high-protein feeding.

⏰ How Often Should I Feed?

Adults can generally be offered a sensible amount of food once daily or every other day, depending on:

• Size

• Age

• Body condition

• Temperature

• Activity

• Food offered

Young growing crayfish may require feeding more frequently.

Remove significant uneaten food to prevent deterioration in water quality.

🌙 Night-Time Activity

Blue Lobsters can be particularly active during the evening and overnight.

Don't be concerned if your crayfish spends much of the daytime hiding and becomes considerably more active after the lights go out.

This can be perfectly normal behaviour.

🦞 Moulting

Like other crustaceans, Blue Lobsters have a hard external skeleton.

To grow, they must periodically moult.

During a moult, the old exoskeleton is shed and a new, soft exoskeleton underneath gradually hardens.

Before moulting, your Blue Lobster may:

• Hide more

• Become less active

• Stop eating

• Behave differently

This can be normal.

⚠️ During a Moult

A freshly moulted crayfish is extremely vulnerable.

Its new shell may initially be very soft.

During this period:

• Don't handle it

• Don't disturb its hiding place unnecessarily

• Maintain excellent water quality

• Keep conditions stable

• Make sure it has somewhere secure to hide

Poor water quality, unsuitable mineral levels and stress can contribute to moulting problems.

🦴 Don't Throw the Old Shell Away!

After moulting you may find what appears to be a dead crayfish in the aquarium.

Look carefully!

It may simply be the empty exoskeleton.

The crayfish may eat its old shell after moulting, helping it recover valuable minerals.

Unless there is a good reason to remove it, the moulted shell can generally be left temporarily for the animal to consume.

✂️ Missing Claws or Legs

Crayfish can sometimes lose a:

• Claw

• Leg

• Antenna

following injury or conflict.

Crustaceans have an impressive ability to regenerate lost limbs over subsequent moults.

However, injuries should never be ignored.

Check:

• Water quality

• Tank mates

• Decorations

• Hiding places

and identify why the injury occurred.

🐠 Can Blue Lobsters Live With Fish?

This needs careful consideration.

Blue Lobsters are opportunistic.

They may catch or injure fish, particularly:

• Slow-moving fish

• Bottom-dwelling fish

• Sleeping fish

• Sick fish

• Long-finned fish

Equally, larger or aggressive fish may injure a freshly moulted crayfish.

No fish should be considered guaranteed safe with a crayfish.

A species-focused aquarium is often the safest option.

🦐 Shrimp & Snails

Small shrimp and snails may be treated as food.

Don't introduce them assuming they'll automatically be safe tank mates.

🦞 Can Two Blue Lobsters Live Together?

Keeping multiple crayfish together can result in:

• Fighting

• Territorial behaviour

• Missing limbs

• Stress

• Injury

• Cannibalism

The risk can become particularly high when one animal has recently moulted.

Individual housing is generally the safest option.

If multiple crayfish are housed together, substantially more space and numerous separate hiding areas are required, but this still doesn't eliminate the risk.

🖐️ Handling

Blue Lobsters should generally be treated as display animals rather than handling pets.

Their claws can deliver a painful pinch.

Handling also creates unnecessary stress and risks dropping or injuring the animal.

If the crayfish needs to be moved, using an appropriately sized container is normally preferable to holding it.

🧹 Cleaning

Daily

• Check the animal

• Check filter operation

• Check temperature

• Remove significant uneaten food

• Check for escape opportunities

Regularly

• Test water

• Carry out partial water changes

• Remove accumulated waste

• Maintain filtration

• Clean viewing glass as required

• Check hides and decorations remain secure

Avoid completely stripping and sterilising a healthy established aquarium unnecessarily.

🚿 Water Changes

Regular partial water changes help maintain good water quality.

A typical established aquarium may require approximately:

20–30% weekly

although the correct amount depends on:

• Aquarium size

• Water test results

• Feeding

• Filtration

• Number and size of animals

Always use appropriately treated replacement water and avoid sudden major changes in temperature or water chemistry.

🩺 Health

A healthy Blue Lobster should generally:

• Explore normally

• Respond to food

• Have normal limb movement

• Maintain its normal colour

• Moult successfully

• Show normal activity for the individual

Learn what's normal for your animal.

⚠️ Signs to Watch For

Seek experienced aquatic or exotic veterinary advice if you notice:

• Repeated failed moulting

• Persistent unusual inactivity

• Unexplained loss of limbs

• Significant discolouration

• Unusual growths

• Persistent refusal to eat outside the moulting period

• Loss of coordination

• Inability to stand normally

• Repeated attempts to escape combined with abnormal behaviour

If something appears wrong, immediately check:

Ammonia – Nitrite – Nitrate – pH – Temperature

Water quality problems should always be ruled out early.

☠️ Be Careful With Medications

Crustaceans can be highly sensitive to some aquarium medications.

In particular, some treatments designed for fish may contain ingredients that are dangerous to invertebrates.

Never assume a fish medication is safe for a Blue Lobster.

Always check that any treatment is specifically safe for crustaceans/invertebrates before use.

🧴 Household Chemicals

Never allow:

• Cleaning sprays

• Aerosols

• Insecticides

• Fly sprays

• Flea treatments

• Paint fumes

• Household chemicals

to contaminate the aquarium.

Aquatic invertebrates can be extremely sensitive to chemical contamination.

🏡 Bringing Your Blue Lobster Home

Before collecting your Blue Lobster, its aquarium should already be:

• Fully set up

• Properly cycled

• Filled with treated water

• At the correct temperature

• Properly filtered

• Tested for ammonia and nitrite

• Equipped with secure hiding places

• Securely covered

• Ready with appropriate food

Aim for:

Ammonia: 0 ppm
Nitrite: 0 ppm

Properly acclimatise your new Blue Lobster to the aquarium rather than simply tipping it straight in.

Give it plenty of time and privacy to settle.

👨👩👧 Is a Blue Lobster Right for You?

Blue Lobsters are fascinating aquarium animals, but they're very different from keeping ordinary community fish.

Before buying one, remember that they:

• Need a properly cycled aquarium

• Require excellent water quality

• Need plenty of hiding places

• Can climb and escape

• Regularly moult

• May rearrange the aquarium

• May damage plants

• Can catch or injure fish

• May fight with other crayfish

• Can pinch

• Are best treated as display animals

• Can be sensitive to aquarium medications and chemicals

For the right keeper, they can be extremely interesting and rewarding animals.

❤️ The Most Important Things to Remember

A happy, healthy Blue Lobster needs clean water, good filtration, secure hiding places, a varied diet and an escape-proof aquarium.

Remember:

🔒 Keep the aquarium securely covered.
💧 Maintain excellent water quality.
🔄 Fully cycle the aquarium before adding the animal.
🧪 Regularly test ammonia, nitrite and nitrate.
🪵 Provide plenty of secure hiding places.
🦞 Don't disturb the animal while moulting.
🦴 Leave the shed exoskeleton temporarily – it may eat it.
🍽️ Provide a varied omnivorous diet.
🐠 Don't assume fish are safe tank mates.
🦞 Individual housing is generally safest.
🖐️ Avoid unnecessary handling.
☠️ Never use aquarium medication unless you know it is safe for crustaceans.

Have the aquarium fully set up, cycled and running correctly before bringing your Blue Lobster home.

🦞 Roxy's Pet Shop

Need help with your Blue Lobster?

Whether you're choosing an aquarium, filter, water conditioner, test kit, substrate, hides, food or decorations, please ask us. No question is too small or silly – we'd much rather you ask.

We recommend having your complete aquarium fully set up and cycled before collecting your Blue Lobster.

Roxy's Pet Shop
Bloxwich High Street, WS3 3LA
☎️ 01922 492521
🌐 roxyspetshop.co.uk

This care guide provides general husbandry information and does not replace professional aquatic or veterinary advice. “Blue Lobster” is a common trade name used for several freshwater crayfish, and exact requirements can vary between species. If you're concerned about your animal's health, seek advice from an experienced aquatic professional or exotics-experienced veterinary professional.