Sunday, November 15, 2009

What the f...ish ?

It is finally raining here now. Monsoon is late but I’m happy it is here. More than me, the crocs are happy. The water level had gone down quite a bit in some of the natural ponds. This resulted in some really tensed days for them. They either had to fight for a dip or defend their part of the ‘pool’ from others.  After the rains you can see a kind of a smile on their face! Rain is good for all. We now see tons of tiny toads and frogs all over the place. You've got to be careful or you’ll step on a few on every walk. They are mostly seen doing two things; eating or getting eaten up! Well, that’s life. Everything seems livelier during the rains though.

I was having a cup of hot coffee in my office, which is in the Croc Bank laboratory building, while it was raining outside. It was cozy inside and I was entering some animal data into the system. Just then Akanksha called.

“There are some fishes walking around in pen 10!”


“Yeah. They are. You coming?”

I hung up the phone and headed towards the said enclosure. On my way, I was wondering what fish could that be. I recalled we did have some Climbing perches. These are often referred to as Climbing gouramis (Anabantidae). They possess a special structure in their head called labyrinth organ which allows them to breathe atmospheric oxygen. Primarily a freshwater egg-laying fish; often guarding the eggs and young. Unlike the name, they cannot really climb perches, unless of course the perches are laid low. Really low.

They are often kept by fish enthusiasts. They look quite dumb with the large eyes, mostly spending time sitting on the floor and ‘looking’ at you. They are commonly seen gulping air at the water surface.

Climbing perches travel in search of water when their ponds dry up; they walk with jerky movements, supported by the spiny edges of the gill plates and propelled by the fins and tail. But what could stimulate walking during rains when the ponds are full?!?

I reached the enclosure and sure the Climbing perches were WALKING!


It was just amazing to see them walking. This was the first time ever I saw a fish walking! Well, I have seen mudskippers before but these were walking on proper land, managing their way through hurdles like leaf litter, stones, bricks.. That was so cool! I remembered that when I take groups for guided tours, I always mention about these fishes. We have a few in Batagur dhongoka and Lissemys punctata exhibits. I tell the group things that I was told about this fish but actually seeing them walking is just another thing.

About 10-15 were out of the water and were walking on the inner side of the enclosure boundary wall. I spent of some time there wondering why are they walking out of water now? I went back to my office as it started raining hard again. After about 20 minutes, Akanksha came to my office with a big smile on her face.

“At least over a 100 were out walking when it was raining heavily! Many are still out.”

Fortunately the rain halted for a while now. I ran out with the camera.

“What the f…ish?!?”

So many of them were walking around, in a straight line! Oh that was crazy! They all came out from one end of the pond and walked for almost the entire distance of the enclosure wall inner periphery. A m a z i n g stamina I'd say! They were following the wall and that’s a long distance considering the size of the enclosure. People who've been here would know. This is Rambo’s enclosure, opposite director’s house. I managed to take the following video before it started raining again.

I still kept on wondering what would make them walk during the rains? In fact they were more active when it was raining really heavily! I noticed one thing this time. There were small puddles along the wall. The fishes would walk to the puddle, halt completely submerging themselves in the little available water, till many of them gathered in the same pool; then they would start walking again. I came to this probable conclusion.[Please note that this is my little theory.  This is what I think.]. With so many of them in the same pond, there must be tough competition for everything including food. So if a water body reaches its carrying capacity, they probably disperse to newer water bodies and populate them. This also means population expansion of the species; one of the main evolutionary goals. Distance from one big water body to another is not fixed. The fish doesn’t know if the distance is long or short. If short, no problem, but if long, the small puddles during the rains provide best pit stops! Plus they are not continuously exposed to predators. Cool thinking!

But wait a minute, I read that they usually walk out under the cover of darkness, but our fishes were walking during the day time! Another mystery to solve, eh? This becomes a bit more complicated especially when there are a few hundred egrets sitting on trees above the pond! Walking in daylight would be just dumb, right? But hey, no predator is active when it is pouring. Wow! How did the fishes figure that out?


madhu menon said...

Soham, very interesting observation. I have also seen lot of mudskippers at different places including in and around Gulf of kachchh. That means there must be a subspcies, that live in estuarin or salty water. Could you please check this?

while reading i was about to tell you the need of documenting such things in detail and in movie mode, then i saw the movie clip. Wonderful..

Anonymous said...

Amazing observation.Well worth to get discussed with some ichtyologists at local universities..


Astronut said...

Hi Soham,awesome march of the 'Gill Brigade'. Maybe next time you'll catch them talking??? Keep up the good work both of you n take care.RajUsha.

Anonymous said...

hi soham, it is really a nice thing, i never knew about climbing perch,its so interesting amd moreover lot to learn from them , how they fiure out about no attack from predators? , they walk in one line, how they figure out direction, how to be in a line ? and most importantly keeping up the stength to cover the distance.
regards bharti