Arapaima – Freshwater Giants of South America
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Arapaima sp. from Guyana. Image: D.J. Stewart
A little bit about a big fish
The groups of species found in the genus Arapaima are part of the family Osteoglossidae, an ancient group of fishes known as the “bony-tongues”. These freshwater monsters have not changed much in the last 13 million years! Large, powerful and covered with an armor of hard, overlapping scales, arapaima are well equipped to survive attacks from piranhas, crocodilians and even people. Arapaima are fearsome predators -prey are sucked in and crushed between their bony, toothed tongue and a bony plate on the roof of their mouth! (See the feeding video below).
Unlike most fish, arapaima need to come to the surface every 15-20 minutes to breath air. They have a weird swim bladder lined with blood vessels which works as a primitive lung. Indeed, if an adult arapaima can’t surface to breathe it will drown! Baby arapaima hatch with working gills but can only breathe under water for just over a week. In the tropics the ability to breathe air is an advantage. This is because the combination of slow moving water, high temperatures and decomposing plant material often deprive the water of dissolved oxygen.
About their ecology and behavior
Arapaima live mostly in lakes, quiet backwaters of large rivers and adjacent floodplains. The tropical floodplain is a unique ecosystem with high and low water seasons, it is neither “terrestrial” nor “aquatic”, but both and somewhere in between. Floodplain plants and animals in the Amazon are highly adapted to annual changes in water height. For example, when water is low, fish can become concentrated in river channels and lakes. However, as waters rise (by more than 10 m in some areas), fish move into the floodplain and feast on newly available plants, fruits, and insects.
Many fish, including the arapaima, reproduce during the beginning of the high water season. Arapaima breed along the edges of lakes and channels in flooded forests. These are no ordinary fish – they build nests by digging a hole using their mouths, sometimes brushing away nearby leaves and branches! What’s more, arapaima parents work together to protect their eggs and young throughout the flood season.
The perils of being a large, tasty fish
For people of the Amazon Arapaima are great eating. The meat has few bones, firm texture, large fillets and tastes delicious. Sometimes called the “cod-fish” of the Amazon, it can be cooked fresh or used later by freezing or salting and drying.
Traditionally, arapaima were captured by fishermen with a harpoon or a bow and arrow. Skilled fishermen wait patiently, and strike quickly when the fish rises up to breathe. Commercial fishing for arapaima began in the early 1800’s, and since then, over-fishing, in combination with increasing habitat degradation, has caused sharp declines in arapaima populations across much of their range. The video below shows fishermen catching arapaima.
Fishermen catching arapaima in Brazil. Images: Rafael Sá Leitão Barboza.
Today, arapaima are faced with continuing habitat loss and insufficient legislation for their protection. In the depths of the rainforest any regulations are tricky to enforce. As a result, arapaima are recognized on two international endangered species lists as Arapaima gigas: IUCN Red List as “data deficient” and CITES “Appendix II”. To ensure the diversity and uniqueness of this genus is preserved, much about arapaima biology and its ecological relations in the wild still needs to be discovered.
Where to see arapaima
Aside from tropical lakes and rivers (and some restaurants or fish markets), arapaima can be found in public aquaria and even in some pet shops around the world. Keep in mind they will outgrow the average aquarium and probably the average aquarium keeper within a couple of years. With enough space and food, they can grow to 1 m in just a year!
Creatures of the Várzea
This entry will be light on text and heavy on pictures just to show you some of the critters I saw last year when I was in Brazil- and I won't bore you with my writing.
Domestic animals (horses and cattle) in the várzea
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Caiman catching (for research of course)
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Turtles and and a Turtle Nursery
And Many, Many More...!
Also, there are a ton of interesting fish species in the Amazon (many are tasty!):
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Many Fish!
And last but not least, the reason why I'm in Brazil, the arapaima!
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Arapaima being harvested at a community lake*
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* – pictures courtesy of Rafael Sá Leitão Barboza
The Trick
Another story from December. Enjoy!
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As my previous blog shows, I took many pictures of the setting sun. In many cases the rising sun was just as stunning. I was just too sleepy to take pictures. I’m generally not a morning person….
The few pictures I took of the sun rising
One morning after watching the sunset with the two fishermen (still early in our expedition), we walked to the next lake. I wasn't used to the hours and the work and drowsily walked with the fishermen. We walked in single file along a path leading from the community to the lake.
Me walking slowly and taking pictures from behind the group
After about 15 minutes on the trail, I saw one fisherman pointing up and saying something. I looked up and tried to spot what he was pointing too, but I couldn't see it. He kept pointing up and even though I didn’t understand what he was saying I scanned the skies for what he was trying to show me. He then pointed down, and there lay a 2 m (~6 ft) freshwater crocodile. My heart skipped a beat and I rushed away from it (I'm glad I was too tired to yelp). The fishermen all began to laugh and I realized the large gash on the crocodile's head... it was dead. It had probably snuck up on a villager with a machete the night before. As I rushed away pale-faced, a fisherman stopped me and told me to take a picture.
Dead freshwater crocodile that almost gave me a heart attack
When it came up later (and it only came up a FEW times), I told them that the joke almost gave me a heart condition- which they thought was funny. The jokes continued until the end of our trip. My shoes were even nicknamed mouths of a crocodile as all the hiking caused the sole to peal from the rest of the shoe (to open like a mouth). And as we hiked, grass would collect in the "mouth" and my crocodile ate; when we walked through water, it drank.
To close their "mouths", I had to stich my shoes
All things considered, it was pretty funny...
The sun set… (back in Dec)
Although I’m already back in Brazil (!), this story is from my expedition last December:
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As the sun set, we were still making our way back to the boat after our first day of work. Our group included seven fishermen, Fabio -the coordinator of the arapaima surveys, and me (the “gringo”). As we walked through dense fields of grass taller than me, the swaying blades in the setting sun made me dizzy and faint. We had only worked since lunchtime, but I was tired, hungry, and thirsty. To make things worse, all the lakes we went to had little or no arapaima and I didn’t see any surface.
Getting to the lake
Less than twelve hours later, we were back on the same trail before the sun rose. I was exhausted and closed my eyes between steps to rest. The trail was uneven- full of cow prints in mud hardened by the dry season. After hiking we traveled by boat and then again by foot. Our entire trip to the lake took more than four hours.
Cow prints made the trail uneven
We surveyed the lake and, unlike the day before, saw many arapaima. It turned out this lake was managed by the local community (three fishermen from that community were part of our team). After we finished the survey, we returned the way we came. We got back after 3pm- our trip to survey one lake took more than 10 hours. It was at least a boost in moral to see the arapaima in the lake.
We were supposed to survey some more in the afternoon but because of some delays (i.e. the lakes we wanted to go to had no arapaima) we had a relaxed afternoon on the boat. As the sun set that evening, the guys turned on the TV to watch a soap opera- it was hooked up to a satellite that required patience and repeated adjustment as the anchored boat rocked and swayed in the water. I instead decided to sit on the roof of the boat and watch the sun set over the river. It really never did get old. As I sat, Lipe climbed up with a mischievous smile. He’s always up to something so I asked him what he was doing. He said he was just joining me. So we talked- I don’t know if he understood me and he generally talked to fast for me to understand… Another fisherman joined us and we chatted a bit more until the mosquitoes drove us under. The sun never sets the same…
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