Photograph by Lozofun

Researchers from the University of Padova in Italy have found that fish have rudimentary counting abilities and can count up to four.

Christian Agrillo, Marco Dadda, Giovanna Serena and Angelo Bisazza studied the ability of Eastern mosquitofish (Gambusia affinis) to discriminate numbers by giving lone female mosquitofishes the choice of joining shoals of between two to eight other individuals in an experimental tank setup.

The authors found that lone fishes more often preferred joining larger shoals that had one more fish.

Test individuals consistently preferred joining shoals of four over shoals of three, shoals of three over shoals of two, and shoals of two over one fish.

However, experiments with larger numbers (5 vs. 4, 6 vs. 5, 7 vs. 6 and 8 vs. 7) showed that the fishes failed to discriminate quantities larger than four.

This demonstrated that the fish had the ability to count up to four and possessed a rudimentary mathematical ability to visually count items if the number is small.

Practical Fishkeeping

Also see: “Female mosquitofish prefer well-endowed males.”

Disclosure: I find this fascinating, perhaps because I raised and conducted experiments involving the consumptive habits of Gambusia (mosquitofish) when I was in the sixth grade. To my parents displeasure, these experiments also involved raising mosquitoes.

Octopus befriends Mr Potato Head

An octopus at the Blue Reef Aquarium, Newquay, has grown quite attached to a Mr Potato Head toy.

The cephalopod can be found playing with the toy for an hour at a time, which contains the added bonus, or maybe more an incentive, of food.

“The secret space within Mr Potato Head allows us to hide tasty treats like fresh crab inside, and that perhaps more than anything has resulted in him becoming such a hit,” said Slater.

Practical Fishkeeping

It’s amazing what I miss when I don’t keep up with my newsfeeds.

Hobby Projects

I’ve been devoting an inordinate amount of time to hobbies lately. I’ve never had a hobby before. I always hated it when people would ask me if photography was my hobby— the first few times it happened, my response was “no, it’s a way of life.” Later I shortened it to “no.” I find it hard to attach the same sort of severity to my latest obsession, trying to keep a couple of planted aquariums. I can’t think of many profound life-lessons in the procedures involved. Or maybe they’re just too obvious:

  • If your chemistry turns foul, you will die.
  • Not enough light will make you depressed.
  • Food becomes fertilizer.
  • Happiness is related to busyness.

I’m also contemplating rock tumbling. Someone claimed that rock polishing teaches patience. I think a more profound life-lesson might be that if you let something grind on you long enough, you become smooth and rounded.