A cost-effective method of preparing larval fish otoliths for reading using enzyme digestion and staining

A fast and cost-effective method for examining otoliths in fish larvae was developed whereby the otolith remains in situ. Whole fish of the clownfish Amphiprion melanopus were enzyme-cleared using a laundry pre-soak and then stained using the Von Kossa silver staining method for calcium. The otolith nucleus, daily rings and the otolith edge were all clearly visible and were suitable for a variety of age and growth analyses. The total 'hands on' time required to process these otoliths was c. 3 min, and multiple samples could be processed simultaneously. The reduction in labour of this method to produce clear daily rings in the otolith lends itself to broad use in fish biology where large quantities of otoliths need to be examined in a cost- and time-efficient manner. © 2002 The Fisheries Society of the British Isles. Published by Elsevier Science Ltd. All rights reserved.