difficulties are immediately apparent in applying this simple definition across the spectrum of reef fish reproduction and complicate the search for a simple, all-inclusive definition. first, since fish may potentially be gathered for some purpose other than reproduction, the proof that individuals in an aggregation are actually spawning may be difficult. direct methods establishing spawning occurrence, such as spawning observations, are best. in many cases, indirect methods, such as female gonad condition (i.e.,presence of females with eggs approaching hydration), are the only feasible method. however, other information, such as the duration of aggregations and movements of fish, are important in assessing other indirect spawning occurrence indicators.