lobed river mullet

The Ludong is herbivorous, eating only the filamentous algae that live on rocks and boulders in and near river rapids. A mature fish weighs from 0.25 to 2 kg (0.55 to 4.41 lb) and costs P4,000- P5,000 a kilo, making it one of the most expensive fish in the country. It commands a very high price in the market because it is seasonal and difficult to catch. It is sometimes called as the "President's fish" because it was known as the favorite fish of former Philippine President Ferdinand Edralin Marcos. This species is known for its unique taste and peculiar aroma when cooked. In fact, its unique taste makes it one of the most sought-after ingredients in making delicious dishes. A study in 2022, by Escaño, et al., was successful in identifying Ludong through genetic barcoding, as Cestraeus goldiei.

This elusive fish is catadromous in nature; it migrates to the ocean to breed. It swims to salt water to spawn from October to December and returns to upstream ponds after. It undergoes upstream migration during December, January, and February, and this coincides with the "ipon-run phenomenon' wherein different species of fish fry also undergo upstream migration. After the ludong had undergone downstream migration, it can be caught in Cagayan River and tributaries.