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Frequently asked questions about fishes

Updated

31/03/20

Australian Museum staff are frequently asked questions about fishes. The FAQ list gives the answers to some of those questions. If your question isn't answered here then you can ask online.

Shrimp and goby on a nudibranch

Fish FAQ - Are sea slugs goby hosts?

John Weinberg sent this image to Dr Bill Rudman at the Sea Slug Forum. The image shows the nudibranch, Ceratosoma trilobatum. John's sharp eyes saw not only the commensal shrimp, Periclimenes imperator, on the nudibranch but also the fish to the right of the shrimp.

Surge Wrasse, <i>Thalassoma purpureum</i>

Fish FAQ - Can fishes change colour?

What causes the colouration of a fish and can it change? Read on ...

Initial phase Yellowfin Parrotfish

Fish FAQ - Can fishes change sex?

Bizarre as it might sound, sex change is quite common in the fish world.

<i>Hoplostethus gigas</i> otolith

Can Fishes Hear?

Yes, fishes can hear, but hearing abilities vary among species.

Ribbon Eel, Rhinomuraena quaesita

Do fish smell?

Well ok, what we really mean is 'Do fishes have a sense of smell?'

A Fathead (genus Psychrolutes)

Do Fishes feel pain?

The question of whether fishes feel pain can elicit very emotional responses from people.

Cottonmouth Trevally, Uraspis secunda

Fish FAQ - Do fishes have tongues?

Most fishes do have a 'tongue'.

Steephead Parrotfish

Do fishes Sleep?

This is a complex question. Deciding if a fish is asleep depends on many factors, one of which is the definition of sleep.

Short-tail Torpedo Ray, <i>Torpedo macneilli</i>

How do Electric Rays produce electricity?

The electric currents produced by some species of fishes, such as the Numbfish and torpedo rays are generated in cells called electrocytes. When an electrocyte is stimulated, a movement of ions (electrically charged atoms) across the cell membrane results in an electric discharge.

Pinstripe Butterflyfish, <i>Chaetodon lunulatus</i>

How fast are larval fishes?

Larval (baby) fishes are not always at the mercy of ocean currents, many are in fact very strong swimmers and can swim surprisingly fast.

Spotfin porcupinefish<i>Chilomycterus reticulatus </i>

How often can a Porcupinefish inflate?

We are sometimes asked about the ability of porcupinefishes to inflate their bodies. Can they only inflate a limited number of times?

<i>Abyssobrotula galatheae</i>

What is the deepest-living fish?

The deepsea has long held a fascination for people. What is the 'fishy depth record'?

Porcupinefish gas bladder

What is a gas bladder?

If you have found a strange balloon-like object washed up on the beach, you may be looking at a fish's gas bladder.

Leatherjacket Louse, <i>Ourozeuktes owenii</i>

Fish FAQ - What is a Leatherjacket Louse?

The images show a female Leatherjacket Louse, Ourozeuktes bopyroides,, that was removed from a Yellow-finned Leatherjacket.

Yellowface Shrimpgoby, <i>Stonogobiops xanthorhinica</i>

What is a shrimpgoby?

The mutualistic relationship between shrimpgobies (also known as prawngobies) and alpheid shrimps, which live together in the same burrow, has been known for many years.

leatherjacket vertebra showing hyperostosis.

Hyperostosis - Swollen Bones

The enlargement of particular areas of fish bones is known as hyperostosis.

Whale Shark,<i> Rhincodon typus</i>

What is the biggest fish?

The Whale Shark, Rhincodon typus, is the largest of all fishes. Whale Sharks between 4 m to 12 m in length are most often seen, but the species can possibly reach a length of 18 m.

Snapper, Pagrus auratus - jaw

Common and Standard Names

Someone asked me about the difference between common and standard names. The video covers this topic and more.

Indo-Pacific Sailfish<i>Istiophorus platypterus</i>

What is the fastest fish?

Measuring the swimming speed of large fishes in the wild is extremely difficult. Which species is the fastest?

Oarfish, <i>Regalecus glesne</i>

What is the longest bony fish?

The Oarfish is reported to be the longest bony fish. It has a ribbon-like body that has been reliably documented to grow to 8m in length, however specimens up to 17m in length have been reported.

Dwarf Goby, <i>Trimmatom nanus</i>

Fish FAQ - What is the second smallest species of fish?

In July 2004, the Dwarf Goby was usurped as the smallest fish by the Stout Floater.

<i>Schindleria brevipinguis</i>

What is the smallest fish?

What is the definition of "smallest"? This seemingly simple question is behind a friendly rivalry that has developed between three groups of scientists.

Underwater life at Lizard Island, 2018

Fish and Fishes

How should the words 'fish' and 'fishes' be used? Some people say that there is no such word as 'fishes'. There is, and its use is simple.

<i>Eviota sigillata</i>

Which species of fish has the shortest lifespan?

The Sign Eviota, Eviota sigillata, a tiny coral reef fish, completes its entire life cycle within an eight week period. This species has the shortest lifespan of any vertebrate.

Bumphead Parrotfish<i>Bolbometopon muricatum</i>

Fish FAQ - Why are they called parrotfishes?

The name 'parrotfish' refers to the fused teeth which resemble a parrot-like beak.

X-ray of leatherjacket

Why are they called triggerfishes?

Triggerfishes (Balistidae) and leatherjackets (Monacanthidae) have a first dorsal fin spine that can be locked into an erect position.

Western Clown Anemonefish,<i> Amphiprion ocellaris</i>

Why don't anemonefishes get stung?

Over the years many theories have tried to explain why anemonefishes are not stung by their host anemones.

Larval Black Dragonfish

Why are the eyes of larval Black Dragonfish on stalks?

Larval Black Dragonfish are long, slender and transparent, with eyes on long stalks that can be up to half the length of the body.

Yelloweye Mullet, <i>Aldrichetta forsteri</i>

Why do mullet leap?

Mullet are commonly seen leaping out of the water. Why do they do this?

A deepsea anglerfish, <i>Bufoceratias wedli</i>

Why is it dark in the deepsea?

You have probably noticed that coral reefs are colourful places. When filmed in natural light, however, much of the vibrant colour is not visible below 10 metres. The underwater world becomes increasingly blue (and eventually black) the deeper you go. Why is this?