The reef that day was filled with plankton. Butterflyfishes drifted through, occasionally stopping to nibble on bits of coral. They were like a school of miniature art models with their protruding mouths and vivid and abstract colours. The warm water current quickened their movements, and they swam through the reef, disturbing millions, probably zillions of swarming plankton.
Just above the shoal of butterflyfish, a half hundred silversides wandered in a different direction pursuing copepods. A sea-like silence pervaded the water. The copepods, oblivious to their surroundings, drifted with the tide.
All of a sudden, the silversides saw before them the diffuse glare of an enormous school of jacks. This was the largest shoal of jacks that the silversides had ever seen before. They were surrounded on all sides and there was no escape ahead or behind, or to the right or left. So they swam deeper and deeper, hoping that they would be able to hide somewhere among the crevices of coral reefs.
Usually, the shoal of jacks would have split up into several smaller shoals. The smaller fish would have separated from the bigger ones. But that day even the heaviest jacks- six or eight years old- stayed together and moved so fast that the great sprawling cloud of silversides couldn’t swim away.
The butterflyfish watched the movements of these darting, wheeling jacks, opening their large mouths gulping silversides, with tension and excitement. They were so engrossed in this show that none of them thought of what would happen once the jacks had gobbled up all the silversides.
In a few minutes, the silversides at the corners of the shoal had been eaten and those in the middle were about to be. The fish darted about, nervous and uneasy. Soon, the hungry, ambitious jacks had gulped down the last of them and were beginning to look around expectantly for their next meal.
Now the butterflyfishes became alert. A few dodged, others hid in the crevices of corals, and a few unlucky ones froze in fear. But it was too late. Neither their fast movements nor their rapid flashing of fins could manage to warn the other butterflyfishes. As a result, a few butterflyfish lost their lives.
And all the other fish- the snappers, pufferfishes, squirrelfishes, surgeonfishes, clownfishes, frogfish, scorpionfish, emperor fishes, whom the jacks did not seek, fled from the dark shadow of the jack shoal. All action stopped. The gills of small fish moved rapidly in and out, and once again a sea-like silence pervaded. All the smaller fish stayed completely still, until the shoal of jacks passed from the patch of reef. Slowly the butterflyfishes placed their protruding mouths out on the reefs, confirmed that the jacks were at a distance and emerged to continue nibbling on the polyps of corals, as if nothing had happened. Their fellow fishes had just been eaten, but there was neither grief nor despair.
The jacks in turn had moved on to another patch of the reef. They were pursuing yet another shoal of silversides. The fishes that had just survived knew that once again the shoal of silversides would be torn by the endless pursuit of these jacks. But there was nothing to be done against such attacks.
The fishes that had just survived knew that once again the shoal of silversides would be torn by the endless pursuit of these jacks. Slowly, the reef filled with the hustle and bustle of fish once again. Eternally occupied with the quest for food, the butterfly fishes browsed peacefully on the reef until the great jaws of big fish were too close.
Edited version of this article http://www.thehindu.com/todays-paper/tp-in-school/a-day-in-the-life-of-a-butterfly-fish/article4899366.ece