# How can you tell how old a fish otolith is?

How can you tell how old a fish otolith is?

## How can you tell how old a fish otolith is?

In otoliths, for example, the seasonal changes appear as alternating opaque and translucent rings. You can count the number of paired opaque and translucent rings, or annuli, to estimate the age of a fish, so a fish with two annuli would be two years old (see image below).

## How do I know my fishes age?

The calcified (or hard) structures of a fish record seasonal growth patterns in the form of annuli (or rings) which can be counted to determine the age of the fish. The most commonly used structures are scales, otoliths (ear bones) and hard fin rays.

How do scales determine age?

Scales are the most widely used aging structure in North America because of their non-lethal ease of collection. Counting the number of annuli (rings) on a scale provides the fish age and the spacing between rings is proportional to the growth of the fish.

### How do you read an otolith?

The easiest way to read an otolith is to take a slice, or cross section, out of the otolith with a special saw and then count the rings under a microscope. However, unless you have access to a low-speed diamond-bladed saw in a laboratory, you won’t be able to age the otolith this way.

### How do you identify the age of the fish under the microscope?

The typical way to determine the age of a fish is by its size. However, this is not a precise method and is really just a way to get a vague idea of whether a fish is young or old. Through microscopy, analysis of bones and scales can reveal growth rings that help identify the age of the fish, as seen in Figure 1.

What is the maximum age of fish?

The life-span may be short, intermediate and long. Whereas the lowest range of life-span (1-2 years) is exhibited by some species of lampreys and teleosts, there are species of dogfishes, sturgeons, paddlefishes, rockfishes and eels which have the life-span (70-152 years) in the highest range.

#### How do you calculate lateral line scale?

Lateral-line scales—scales bearing the lateral-line canal from the head to the end of the vertebral column (end of the hypural plate). If the lateral line is not complete, continue the count along a row of scales from the last pored scale. This count is sometimes referred to as the lateral-scale count.

#### How is growth and age determined in fish?

Aging fish is similar to aging a tree by counting the number of growth rings. However, the age of the fish is determined by counting the number of wide growth rings called annuli.

How do you clean otoliths?

Decontaminate otolith by sonifying in a series of distilled, deionized, reverse osmosis water baths (Super Q or Milli Q water) in acid-washed polyethylene vials. Brushing with an acid-washed nylon toothbrush under a flow of Super Q water can be used to remove any adherent tissue before the first sonification.

## Can fish hear you talk?

However, yes, they can hear your voice. They just know someone is speaking. They can associate sounds with action, though. For example, if you are to say your betta fish’s name – let us call him George – each time you sprinkle food in his aquarium, he will eventually associate the sound of “George” with food.