Did you know...

The glass of the main exhibit tanks is actually made of acrylic, not glass. This is because acrylic is stronger and produces less distortion. It is 28cm thick!

At any one time, 4000000 litres of water are in the Aquarium's tanks!

The Aquarium was home to a 150kg shorttail stingray, but unfortunately it died.

Do fish feel pain?

When a fish is caught on a hook and line, it can definitely feel through its nervous system that it has been hooked, and will try to escape.  Unlike humans, most fish have no frontal lobe in their primative brains and so they are not likely  to be distressed by what they feel.

How do fish produce sound?

The gas-filled swimbladder is used to make or amplify sounds.  Muscles attached to the swimbladder are contracted to produce sound waves that are heard as growls, yelps, whistles, grunts, hoots and drumming noises.  These noises are used to chase away predators or attract mates.   Ganters and Kobs are well known fish that produce sounds.

Why do fish have swimbladders?

Swimbladders help fish to adjust their bouyancy.  Gas is pumped in or out to change the bouyancy of the fish.  If a fish is pulled too quickly to the surface, the gas in the swimbladder cannot adjust quickly enough to the decreasing pressure.  The bladder the either bursts or pushes the internal organs out of the mouth.

Why do fish have scales?

The scales on a fish's body protect it from predators, parasites and sharp rocks as they form a flexible armour coating.  The rows of scales bend with the swimming movements of the fish to make a streamlined body over which the water flows smoothly.  Scales are also used to store essential minerals, such as calcium, which are absorbed when needed.

What are endemic fish?

Endemic fish are fish that are restricted to certain  areas because of water temperature or tides.

How do you tell the age of a fish?

Regular rings are laid down on the scales. If they are laid down once a year then it is easy to tell the age of the fish.

How do the different fish feed?

Steenbras blow prey out of the sand.

The Baardman uses a chin barbel and Gurnards use modified rays of the pectoral fin to find buried food.

Mullet sieve plankton from the water using rakers on their gills.

Rays and Sand sharks trap food under their flattened bodies and feed from ventral mouths.

Musselcrackers and Sand sharks crush shellfish with powerful jaws and teeth.

Electric rays stun their prey with an electric shock.

Do fish grow all the time?

Yes, fish grow throughout their lives, but they grow slower as they grow older.

Fin positions

You can predict the behaviour of a fish by examining the arrangement and shape of their fins.  If the pectoral fins are high up on the body, the pelvic fins are far forward and the tail fin is blunt ended then it is probably a slow swimmer.  If the pectorals are back and it has a forked tail then it is probably a fast swimmer.

Fish with a roving eye?

Imagine a fish lying on its side in the sand.  Its eyes have no eyelids.  What happens to that lower eye?   Flatfishes have the solution - they just move it!

The young flatfish has eyes placed on either side of its head.  It swims in the plankton.

As it grows one eye moves to the top of its head and the dorsal fin grows forward.

The adult flatfish lies on its side in the sand.  Both eyes are now on the upper side and can focus independently of each other.