Thursday, December 3, 2009

Parrot fish

Parrot fish are named for their dentition; their numerous teeth are arranged in a tightly packed mosaic on the external surface of the jaw bones, forming a parrot-like beak with which they rasp algae from coral and other rocky substrates(which contributes to the process ofbioerosion). Many species are also brightly coloured in shades of blue, green, red and yellow.

Although they are considered to be herbivores, parrotfish eat a wide variety of reef organisms, and it is important to note that they are not vegetarian. Species such as Bolbometopon muricatum include coral (polyps) in their diet. Their feeding activity is important for the production and distribution of coral sands in the reef biome and can prevent algae from choking coral. The teeth grow continuously, replacing material worn away by feeding. Thepharyngeal teeth grind up coral rock that the fish ingests during feeding. After they digest they excrete the rock as sand helping to create small islands and the sandy beaches of the Bahamas and Caribbean. One parrotfish can produce 90 kg of sand each year.

Maximum sizes do not vary widely within the family, with the majority of species reaching 30–40 centimetres (12–16 in) in length. However, a very few species, such as the bumphead parrotfish reach up to 100 centimetres (39 in).

Their bodies are deep, with large, thick cycloid scales, large pectoral fins and homocercal tail fins.

Parrotfish use their pectorals as their primary means of locomotion, engaging the tail only to achieve higher speed.

Some females can turn into males.

Life Cycle

The development of parrotfish is complex and accompanied by a series of changes in color termed polychromatism. For most species, adult males and females have different color. The females are usually drab tones of green, brown or gray, while the males are a vivid, neon color. In the Mediterranean parrotfish (Sparisoma cretense), the females are brightly colored and the males are a drab grey.

In most parrotfish species, juveniles have a different color pattern than adults. Juveniles of some tropical species can alter their color temporarily to mimic other species. As juveniles mature they enter what is termed the initial phase coloration during which they may change color and gender. For most species, initial phase fish are males and have the beginnings of adult male coloration. However, initial phase fishes may include generally mature females. The many color varieties seen in parrotfish are part of the different phases of development that parrotfish go through.

Feeding parrotfish of most tropical species form large schools grouped by size. Fights of several females presided over by a single male are the norm in most species, the males vigorously defending their position from any challenge. If the dominant male of a school is removed, one of the females will change gender and adopt the dominant male role.

Parrotfish are pelagic spawners; that is, they release many tiny buoyant eggs into the water which become part of the plankton. The eggs float freely, settling into the coral until hatching.

parrot fish fight

Wednesday, December 2, 2009

Piranha Fish

The Piranha species is a very noted fish especially from TV. It’s aggression and hunger for everything what moves in the water are well known facts. They are shown as cruel and merciless beasts in the TV. So why do people keep them? Aren’t such people only criminals who drop their victims into the tank with Piranhas in order to hide their crime? Not everyone knows that Piranhas bite only if they are hungry, or something bleeds in their aquarium. So basically, a wise and skilled fish keeper will not be bitten or even eaten (it’s a myth that few Piranhas can eat the whole man’s body). Their attacks towards humans are very rare in the wild. The natives from the locations where Piranhas live are swimming with them a lot and they haven’t been harmed. However, nowadays it is not recommended to do so because as the environment changes all around the world, the fish’ behavior may change as well. Generally, they have less food so they can be much more aggressive against humans than before. There are no reports of killing a human by Piranhas, only when a human died in the water and they eat him later.

An illegal fish

Did you know that they are illegal in some states in the U.S.A? It is in the states with warm environment. Some people could put them into the rivers and they could destroy the normal environment in those waters because they would not have natural enemies there.

In order to understand this fish, we have to learn more about them

Piranhas are freshwater fish and they come from the Amazon, Guiana and Paraguayan basins in the South America where we can find innumerable living creatures (including fishes). These geographical locations are even the most settled places in the world, so you can imagine how much dead animals can fall into the water. This is the reason why Piranhas have to have such big appetite. Naturally, such rivers require fish which eat dead animals, so the decomposing meat will not contaminate the water. They have very sharp teeth so they can eat all the meat from the bones of the dead animal. Of course, they hunt for live food too, but usually smaller fish.

Conditions in the aquarium

In aquarium they require temperature between 24 – 28°C. The pH value should be a bit lower, just like the dGH. The aquarium has to have places for hiding; Something like caves, some driftwood, plants and everything what you can find in their natural environment besides an strong filter. They produce many excrements so the filtration must be very effective. They also need a big tank. If they haven´t got enough place they turn into cannibals.

Do they eat meat only?

There are many types of Piranha fishes. You can even find Piranhas which eat vegetables only. Moreover, we even don’t know all the Piranha species because new and new species are found often, but right now we know more than 70 different kinds of them. This difference consists in the colors and in the behavior as well. In addition, some of them are more and some are less aggressive.

The Body

They are from 15 to 30 cm long. Piranhas can have many different colors and shapes of the fins, but they have something in common. The most visible characteristic are their teeth. Their mouth is a bit open and you can see their triangle small sharp teeth. They have round body with massive mouth.

Feeding habits

This fish is a meat eater. A mature individual can eat pieces of fish meat, beef meat, chicken meat, or you can feed them with feeder fish especially if those fish are alive. But if they are small, they eat flakes and some worms. On the other hand, if you keep vegetarian piranhas, they eat plants in your aquarium, some vegetables, or vegetable flakes and tablets.

A community fish?

People think, that they are shoal fish and that they aren’t aggressive towards each other. But it is not true. They are in shoals only if they feel danger, for example if they are chased by river dolphins, or if they are going to eat a big animal. They should not be in one aquarium with other fish species, because they will eat them. Of course there were some cases when smaller non-piranha fish have nipped fins of the bigger Piranha, but it is nothing strange when an aggressive fish is not aggressive to fish with which it has lived from the juvenile age. But not every time it can work, so you shouldn’t risk it. They are very territorial fish and because of this you should have them in a big aquarium, so every fish has it’s own place.

Piranha Attack

Black Piranha

How Do Fish Sleep?

How Do Fish Sleep?

Yes fish sleep. But it’s not sleep as we know it. They don’t have eyelids to close, they sometimes do it during the day, they don’t show the characteristic brainwave patterns like REM sleep seen in humans, and some, including most sharks have to keep swimming in their sleep.

But fishes do have a period of reduced activity and metabolism which seems to perform the same restorative functions as nocturnal sleep does in humans. Some are more obvious about it than others and actually rest on the bottom or in coral crevices, and parrotfish secrete a mucus “sleeping bag” around themselves before they go to sleep. If you get up quietly in the middle of the night you will find your goldfish in an almost trance- like state, hovering near the bottom of the tank making just the minimum correcting motions with its fins to maintain its position in the water column. If you put food in when they’re like this they take noticeably longer than usual to respond, as if they have trouble waking up.

Mr. Oliver Crimmen, Fish Curator, Department of Zoology, The Natural History Museum

How can you tell if a fish is asleep?

In human terms, they don’t have the type of day / night lives that we recognise on the old 9 to 5 routine. Some fish are active by day, others by night. Many fishes live quite still lives on a regular day / night cycle. (Deep down it’s pretty dark anyway!)

Some deep ocean fish appear never to stop moving (often said of some sharks who have to keep water and oxygen flowing through their gills).
Most fish do rest. A bit of ’shut eye’ is difficult for most fish as they don’t have eyelids except for sharks. Most fish ’switch off’ when safe to save energy and go into daydream mode. You can see this in a fish tank or aquarium – some float motionless in place, some float near the bottom of their tanks, some build nests or nestle themselves into the seabed or coral for safety and camouflage.
They might look but like most resting animals are alert for danger whilst resting or “sleeping” saving energy. What exactly is going on in their brain (and human type sleep / brain waves) would be harder to tell. I’ve no idea if they dream either. However a recent bit of research (featured in a Times article in October 16 2007) suggest they even get sleepless nights if you keep annoying them!
“Researchers have now been able to show not only that [zebra] fish sleep, but that they can suffer from sleep deprivation and insomnia. By repeatedly disturbing the fish using mild electric shocks, researchers were able to keep zebra fish awake at night. Those fish that had suffered a disturbed night were found to catch up on their sleep as soon as the opportunity arose.”
Mark Norris, Education Officer, Newquay Zoo

sleeping fish

do fish sleep?

Tuesday, December 1, 2009

Oscar Fish

Oscar Fish
The Oscar Fish, or to give it its scientific name, Astronontus ocellatus. Astronontus actually means being marked with a star on the back. Ocellatus means bearing an "eye spot" The Oscar is a fresh water fish that is a member of the Cichlid (pronounced sick-lid) family which is native to the Orinoco, La Plata, and Amazon river in South America where they inhabit the many slow-moving rivers & lakes in the Amazon Region.

There are only two seasons in the tropics, wet and dry. Six months of the year, 120,000 km of rainforest is flooded with water as deep as 20 m. The Amazon holds 10 times more water than the Mississippi. More water flows through the Amazon in one day than it does in the Thames in one year. The Amazon river is home to some of the largest fish in the world including massive catfish and the elusive Arapaima which can reach lengths of over 4 m.
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