It’s Christmas. In Poland, where I come from, the biggest celebration is the Christmas Eve dinner. Many families eat the same traditional dishes every year, and among them is carp, a fish that is often associated with Christmas.
When I was little, my dad used to buy live carp and they would occupy the bathtub for a few days before Christmas. Sometimes I would watch them, but they did not seem very interesting to me at the time. However, they were confined to the small space of the bathtub, in an environment without any enrichment. I did not know then that, when moved outside of such dull environments as a bathroom or a small fishmonger’s pool, carp are a lot more interesting.
Learning its way about
Carp like company and get stressed when they are completely alone. Their spatial orientation and memory are well-developed. Even in a turbid lake, they can travel hundreds of metres between their daytime refuge (they are more active during the night) and places to forage for their favourite food. When one fish finds a new feeding spot, it can go to the same spot the next night, and other carp follow it, and quickly learn where to feed. In the lab, carp that knew where to find food were even observed swimming from the feeding location to a group of newly introduced fish and back again, helping naive individuals find food. Could that be a sing of altruism?
Carp with character
Like many other animals, carp have personalities. They differ, for example, in how they react to a new place. Some check it out quite quickly, while others take longer to leave their safe hiding place. The bolder fish are also better at competing for access to food, being “pushy” without using direct aggression. The personality of carp also affects whether and how they learn.
Researchers studied carp in an aquarium with two smaller chambers marked with different colours. In one of them (always of the same colour, though in a random location) was food. Most of the bold carp did not pay attention to the colours, but simply first checked one of the chambers at random, and when they did not find food there, they immediately swam to the next one. The more cautious carp usually learned that one of the colours meant food and swam straight to the correct compartment. Some of the bolder carp also learned to react to the colours, but it took them longer to learn than the cautious fish. It reminds me of two types of people – some observe and draw conclusions first, then proceed to action, and others quickly rush to action without paying attention to details.
These are just a few examples of the carp’s cognitive abilities and we still don’t really know much about them. But the goldfish, which is closely related to the carp, can even be taught all kind of tricks. I am therefore convinced that carp, if studied more, will amaze us with their abilities.
And this year for the first time I broke the tradition and instead of fish I had vegan “fish sticks” during the Christmas Eve dinner.
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Photo: Karelj – Own work, Public Domain, https://commons.wikimedia.org/w/index.php?curid=14665758