Fish are familiar to everyone. There are four types of fish body shapes: spindle-shaped, laterally compressed, club-shaped, and flattened. Some fish are covered with scales. So, which method helps determine a fish's age? Look at the tail or the scales? Let's find out.
Which method is helpful in determining a fish's age? Looking at the tail or the scales?
Examining a fish's scales can help determine its age. Under a microscope, the scales reveal alternating black and white rings, resembling tree rings. By counting the number of rings on the black areas of the scale and adding one, you can determine the fish's age.
How else can you determine the age of a fish?
1. Weight
Fish vary significantly in weight depending on their growth stage. For example, carp hatching from eggs weigh only a few grams. It takes about a year for them to grow from fry to fingerlings, reaching a weight of about half a pound. In the second year, they can reach about 1.5 pounds, and by the third year, they can grow to 3 pounds. For anglers or fish farmers, measuring a carp's weight allows them to estimate its age, although there may be some error, it won't exceed one year.
2. Otoliths
Otoliths are calcareous stones unique to the auditory bullae of vertebrates. Most teleost fish species have similar organs, although the size of the otoliths varies among different species. The otoliths of the bass are the largest, followed by those of the cod . Smaller fish such as crucian carp and whitebait have very small otoliths, while those of cartilaginous fish are generally well-developed. As fish age, concentric rings appear in the central area of the otolith, very similar to the rings on fish scales. The number of these rings corresponds precisely to the fish's age. This method of determining age is highly specialized, requiring the otolith to be dissected at its core to visualize and count the rings. Therefore, this method demands considerable expertise.
