The Clownfish – Better known as Nemo

I recently saw Dr. Peter Buston from Boston University speak about his research on the clownfish Amphiprion percula. The talk reminded me of some fun clownfish facts.

Clownfish can live over 30 years. That means there are clownfish out there older than me!

Clownfish live in anemones that keep them protected from predators with their stinging cells. The fish are immune to those stings and predation is pretty much a non-issue because of this relationship. Maybe that is how they live so long!

When eggs hatch the larvae are dispersed into the water and rarely settle on their family anemones (this makes sense when you think about genetic diversity). Makes you wonder how Nemo ended up in the same anemone as Marlin in “Finding Nemo.”

Each anemone can have a group of clownfish living in it – a breeding pair and possibly some others. The group dynamic is based on a size hierarchy – the largest and most powerful fish is the breeding female. In these pictures from Horn Point Lab you can see that the size difference in breeding pairs.

If the female dies, the next largest male then rises to the occasion – literally. The male will turn into a female and the most dominant fish in the group! That gives a whole new twist to “Finding Nemo” – Marlin would have become Mandy after Coral got eaten by the barracuda at the beginning of the movie.

When I worked at Horn Point during college (the same place I learned more about Blue Crabs) we had a few projects going on with clownfish. The lab was doing feeding studies to learn what food would make the clownfish grow the fastest and have the best coloration. The idea was to figure out how to breed the best-colored clownfish fast for the aquarium trade. Using aquaculture to breed clownfish is a better option for aquarist because the fish aren’t taken from reefs in the wild – sometimes by environmentally damaging methods like cyanide fishing.

The clownfish were by far the favorite animal of the school kids who came through to visit over the summer. One thing I remember about the clownfish is that they were quite territorial. We would put terracotta tiles in the tanks for the females to lay their eggs on – mimicking the hard surface that an anemone would attach to in the wild. Then the female would lay her eggs and after several days we had to take the tiles out of the tank, transfer them to another tank, and count all the eggs. 


It was the lab joke to have the newest person reach in to take out the tiles – without telling them that the fish would fight for it! I remember them drawing blood a few times. In high salinity water, that wasn’t a good time but watching the babies hatch out and grow was totally worth it.

Visit Dr. Buston’s website to learn more about his research.

Photos by Sara K. MacSorley