Dan Lorbeske
We were reading about the air-breathing catfish from the mystery picture today and a
student came up with a question for you about it. She wants to know if it's considered an
amphibian because it survives out of water for awhile, or if it's simply a fish. Submitted by C.R. Hanna
Air breathing catfish, and other types of air breathing fish a much more common than people
think. Many times fish that live in warm or tropical waters will adapt to going to the surface
to get a gulp of air to suppliment the intake by the gills in the water. As water gets warmer
the amount of oxygen it can hold decreases, and just like you, fish need oxygen to live. In
some cases there is not enough oxygen in the water to support the fish so they have to go up
to the surface to get some air. Now ther are some fish that take this to an extreme, the walking
catfish which can actually leave the water for short periods of time to try and find a better body of
water. These fish have a very thick mucus that covers them during this time which helps to store some
oxygen, walking catfish do not have lungs so they aren't really able to breath air, so if this mucus dries
up they will die. Now the fish thathas taken it to the greatest extreme are the lungfish.
These animals actually have a lung-like organ that they can take air into. It's pretty much just
a sac with a lot of blood vessels around it that capture and distribute oxygen. The Australian and
African species use the lung when they are dormant in mud puddles to get them thru the dry season, but the
South American species has gone one better and it's gills regress as it ages so it now has to breath air all
of the time. Now, even though they can breath air they are still dependent on water to live and on
a phisiological level, have more in common at this point with fish than amphibians. Sorry for the long
winded answer.
Where does a silver arawana fish live? Submitted by Dunne Elementary
The Silver Arawana is found in South America, in the Amazon River basin, Rupununi and Oyapock Rivers.
This is something i dont see everyday but, How can a catfish breath air?
Would it dry up and die? Submitted by Amboy
I think the species you're thinking about is the walking catfish, which can walk for
short distances over wet ground to find new pools of water to live in. The walking catfish
isn't truely an air breather, it has a very thick mucus that covers its body that
helps with the transfer of gases both thru the gills and thru the animals skin. If
the mucus over the fish were to dry up though, it would indeed suffocate.
Do you take care of some of the animals? Submitted by Hibbard School
Yes, I do take care of the animals in the Amazon Rising exhibit. The exhibit includes many kinds of fish, including Red Bellied Piranha who really are quite docile, despite what you may have heard about them, birds, turtles, frogs, two snakes, the Emerald Tree Boa and Green Anaconda, two Callimico monkeys, and my favorite invertebrates including, but not limited to, Goliath Bird Eating Tarantulas who rarely eat birds, and South American Bullet Ants.
Do you ever get to go to the rainforest? Submitted by Alexander Junior High
As of now I have never gotten to go to the rainforest.(
Why did you want to become an expert on the rainforest? Submitted by Washington
Elementary
My passion began at a young age when I fell in love with the small tetras and catfish that live in the Amazon River, in particular the corydoras and sucker mouth catfish as well as the small characins (small tetras like Neons and Cardinals). As I grew I tried other things, frogs and snake mostly, but I always gravitated back to the little tetras and catfish. I decided to try and make a career of it and took many ichthyology and ethology courses in college worked in the fish department of a small pet shop for six years and then at a state fish hatchery for a few months before coming to the Shedd. I was very fortunate to get hired in the Amazon Rising exhibit which housed the animals I had always loved and it was here that my passion grew to include the insects found in the forest as well as the fish and the relationships these animals have with others and the environment in the rainforest. So I guess it was less of a desire to become an expert and more of result of following my passion for these animals.
We read that the animals are harder to see when the river has lots of
silt in it. Does this hurt the fish? Where do they go if there is too
much silt?
Whether or not a high level of silt will be harmful to fish depends on if the fish are used to it or not. Some areas of the river have always had high silt content just because of the environment that surrounds the river. If the fish have evolved in an area that naturally has high silt content then they will be adapted to the high turbidity and it will not be a problem. When an area of a river experiences raised levels of silt, usually due to run off often a result of heavy logging of an area, this could cause problems for the animals in the system. The animals may not be well adapted to finding food in waters that are now much more turbid, and a lot of the food some of the fish eat are small crustaceans that live in the substrate of the rivers. The more sediment that enters the system the more clogged with tiny particles the substrates will become and may force many of these invertebrates to seek new homes and the fish may not have a very high abundance of food and will either have to try to find a new habitat up or down stream, or they may not survive. Unfortunately some fish are very specialized and adapted to a particular water type, and may not be able to adapt to water with a higher turbidity, and may not be able to adapt to different areas in a river.
What kind of fish do they have at the Shedd Aquarium? Do you have piranhas?
What do they feed them?
We have more types of fish than I could possibly go thru in our Amazon River exhibit here at the Shedd, some of the groups of fish we have include, characins, catfish, sucker mouth catfish, pacu, arrowana, arapaima, lungfish, cichlids, electric eels, knife fish, algae eaters, tetras, pencilfish, freshwater sting rays, even the awe inspiring Zebra Plecostomus and yes we have Red Bellied and Black Piranha. The Piranha get a few different types of foods including prepared gel diets, smelt, and students that bang on the glass… Ok, they won’t let us feed the last item, and in all honesty the piranha would probably be afraid of them if we did. Piranha are a much over dramatized and misunderstood fish. They are not the bloodthirsty beast that Hollywood would have us believe that they are, in actuality they much prefer eating dead animals than chasing down live ones, and most of the aggression we see with ours is between piranha and other piranha. We even have divers go in with them and clean the exhibits. Now, this is not to say that they should not be treated with respect, as they are capable of doing massive amounts of damage with their jaws, but usually fits like these are sparked by starving fish. We keep ours well fed which greatly reduces the likelihood of aggression.
Do the fish eat spiders?
Indeed fish do eat spiders. I think you will find that fish, in general, do not have discriminating pallets. In short, if something can fit into a fish’s mouth, or the fish thinks it can, it will probably try to eat it. We actually feed crickets to our fish at the aquarium, and small spiders would make a delightful treat to a lot of the fish here.
What is the water (in the river) like? What color is it? Can you see the bottom?
Can you see fish from the boat?
Is the river water dirty? Can you drink it?
All right, these questions are all very similar, so I’m going to field them at the same time. The water in the river is very wet, it greatly impedes the dryness of most things that enter it; towels are recommended to counteract the dampening forces of the river. I jest. The water clarity, color, and appearance vary greatly depending on where you are on the river. The Amazon River is huge, it traverses the width of South America so it changes it’s characteristic in different areas. There are three major delineations of water in the Amazon River, clear water, white water, and black water. Clear water is water that is relatively free of particles in the water coulomb that would cloud it up. White water isn’t white; it’s more of a milky brown color due to the high levels of particulate matter in the water coulomb. You won’t be able to see very far into the water. Black water isn’t black, it looks like tea, and the color is due to the large amounts of tannin that is leached into the water system from the roots of trees. This makes the water very soft and acidic as well. Now there are water types everything between these three as well, these are just the prevalent water types that much of the river can be divided into. Whether or not you can see the bottom depends upon the depth, lighting, and turbidity of the water. Whether or not fish are viewable depends on turbidity and the kind of fish in the area. You can have very clear water and if the fish are cryptic you may not see them even if there are hundred of them, also, you could be looking at water that is murky as you can imagine, but if there are large fish like an Arawana or Arapaima cruising around close to the surface, you would probably see them. As far as the river being dirty, or having drinkable water, yes, the water is drinkable; the native people drink it with no problems. Now, if you were going to visit the Amazon you would probably want to treat the water with iodine to kill bacteria as your digestive systems will not be accustomed to the bacteria in the water there and the water may make you quite ill where it would not bother someone that is used to it. There are probably parts of the river that have pollutants in it as well and you may not want to drink the water in these areas. You’d have to check and see.
Does illegal logging hurt the river and the animals that live in it?
Illegal logging certainly does impact the river systems. When trees are cut down close to a river, it can change the environment around the area it was cut down. What once may have had excellent shade and good cover during the day may now be wide open under bright sun. Areas that were calm may be very windy and turbid without the trees around to break the wind. Even trees cut down miles away from the river can impact it. The root systems of trees help to keep soil in place on the ground, if the trees are cut down the soil will now run off in rain showers and may end up in the river. This can cause siltation, a process by which tiny silt particles enter a water system and start to clog up the substrate and make the water much more turbid.
What kind of plants grow under the water?
There are a lot of different kinds of plants that live under water. Plants in the genus Echinodorus are quite common in the Amazon River (sword plants for those in the aquarium hobby), which have large broad leaves, and there are plants that look like grassy fields underwater, some plants like hyacinth float on the water and live in large colonies creating a floating meadow ecosystem, and lets not forget an abundance of algae. The plants that live under water in a rainforest are often as specialized to the environment as the terrestrial variety. Some have adapted to intense light, while others thrive in dim setting, others prefer rapid flowing waters, and still some like it stagnant. Fish and aquatic invertebrates also take advantage of the aquatic foliage using it for cover to avoid predators; they may lay eggs on the leaves of the plants, and even use the plants as a source of food. The plants have come up with one or two strategies of defense to ward of hungry fish including thick tough leaves, foul taste in the leaves, and even just growing so fast that it doesn’t matter if the fish eat them.
What happens when a fish or river dolphin is killed in the river?
If dolphins, fish, or most any animal in the river dies it will most likely become food for the other animals. Many of the fish in the river systems are purely scavengers, one of the most well known scavengers are Piranha. Even though they have a very bad, and mostly undeserved reputation as being vicious fish, they would much prefer to find a free lunch than have to work for it. You can be assured that no animal goes to waste when it dies, the other animals will use it to sustain themselves.
Are they any fish who light up in the Amazon?
I am not aware of any bioluminescent fish in the Amazon River. A lot of people think that Cardinal Tetras, Paracheirodon axelrodi, and Neon Tetras, Paracheirodon innesi, would glow because of the vibrant blue and red coloration of the fish, but in actuality, the colors are caused both by pigmentation in the animals skin, and light refraction from the scales. Now, this does not mean that there are not bioluminescent fish in the Amazon, new fish are being discovered all the time and some of the trenches in the river can be over 150 feet deep!
What kinds of animals do you see when you're on the boat?
Well, I've never had the opportunity to go and spend time in the rainforest areas, but from what I've heard the animals are quite cryptic and you may not see as many as you would think from the boats. You may see caiman floating about in the water, birds fluttering thru the sky, and of course, copious amounts of insects will be buzzing about at any given time. Generally the water in the rainforest rivers is very murky so you probably can't see very far into it. I don't think it will be until you get out and really start looking for the animals that you will see a lot. Remember, the areas around a large river are very open, animals that venture out into them are no longer under cover and are at risk themselves.
Why do people sell endangered animals as pets?
The biggest reason that people sell endangered animals as pets is for the money. Rare animals will just about always fetch a higher price than common animals. It is important to remember that the collection and sale of animals is how a lot of people make their livelihood. We don't like to see the illegal sale of animals that are having a hard time in the wild, but some people have relied on the sale of some of these animals to support their families for generations, then one day, it's illegal to do it. That would be like someone saying it's no longer legal to display animals in a public aquarium, I'd be out of a job, and if there was not feasible alternative source of income, I might be tempted to display the animals even though it's against the law. One must also remember that it is generally people in other countries, the U.S. being a large source, whom are paying the big bucks to get these animals and keeping the trade alive.
What kinds of fish do people eat in the rainforest? What does it taste like?
I have never been to the Rainforest myself, so I don't have a first hand account, but from what has been relayed to me from friends who have had the opportunity people eat a wide array of fish in the rainforests. Peacock bass, Pacu are supposed to be a favorite from the sweet flavor in the meat as they eat primarily fruit, Arapima, Piranha, large catfish, and even sucker mouth catfish are eaten. Pretty much anything that is catchable and large enough to eat will be consumed, stingrays included. Having never the pleasure, I don't know what the fish tastes like.
How do people catch fish in the rainforest?
There are many ways of catching fish in the rainforest; I believe various ways of netting are going to be the most prevalent. These involve setting nets out of various constructions, in various places, and at various depths of the rivers. The nets are designed to "funnel" the fish into capture nets that they won't be able to swim out of. The construction and placement of the nets will vary depending upon what kind of fish is being targeted to catch. A popular way of catching smaller fish is to use sane nets. This process uses a couple or a few people and a large net with several handles on it. The people wade out into the river where large schools of small fish are and kind of walk towards them and surround the fish with then sane and pull them up. There are also more traditional fishing methods such as spear fishing, and I'm sure the rod and reel is used, as some of the larger fish are good for sport.