How is the age of a fish determined?

Answer 1

That all depends on how much your willing to spend on the fish. Some vets can check thing like age, and gender of fish, with different test but i warn you now it is EXPENSIVE! On certain types of fish you can count the nuber of dots on the large scales running down the sides of the fish. Count the dots on the largest scale, ONLY, this works best on carp species. Those being goldfish, and koi types. But the only fool proof way is to have your vet check for you.

Answer 2

Scales, bones, fin rays and otoliths have all been used to determine the age of fish, since these and other bony parts of fish often form yearly rings (annuli) like those of a tree. However, otoliths generally provide the most accurate ages, particularly in old fish.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.
If the otolith is thin enough, it may be possible to count the annuli without having to prepare the otolith first. Try measuring the thickness of the otolith. If it is 1 mm or less, or if the thickness is less than 1/8 that of the total length, you may be in luck. If you can see alternating light and dark zones, you're probably looking at annuli. They probably won't be as clear as those in a cross section, but they should look roughly similar.




If annuli aren't visible in the whole otolith, you'll have to crack the otolith in half, then lightly burn it, to make the annuli visible. To do this, you'll need a dissecting microscope, a piece of clay or plasticine, forceps or tweezers, an alcohol burner or candle, and some vegetable oil. To start with, you'll need to break the otolith along its centre (length-wise). The easiest way to do this is to place the otolith flat on the pad of your index finger, sulcus side up. The sulcus is the groove carved into the top of the otolith, and is usually found on the convex side (outward-facing curve). Take your thumb nail and place it over the otolith centre. Then press down firmly until the otolith snaps in half. Large otoliths can take A LOT of pressure before breaking. If you can't break it, try using pliers. But keep in mind that it's harder to control where the otolith breaks with pliers. And an otolith that's broken too far from the centre line cannot be aged.

Answer 3

The age of a fish can be determined by examining the rings in one of the scales of the fish.

Answer 4

Fish have bones in their heads called otoliths (oto’ meaning ear and lith’ meaning stone). These bones help the fish to keeping its balance in the water. When an otolith is removed from a fish, sectioned into thin slices and viewed through a microscope, it reveals a pattern of light and dark concentric rings.

When a fishes’ grow slows in the winter a darker denser ring forms. In the warmer months when a fish is growing faster and a clearer ring is formed. These yearly growth rings are called annuli, which are similar to the rings found in tree stumps. You can count the rings in the otolith or stump and determine age

Answer 5

The internal layered structure of the otoliths of the inner ear of a fish has proved to be a relatively reliable method of determining the age of many different species of fish.

Answer 6

Fish are born, live and die like we do only you can’t ask a fish its age. When a fish is spawned in a hatchery the manager knows how old it is. That’s called a known age fish. If you catch a fish in the wild telling it’s age is a different story.

Fish have bones in their heads called otoliths (oto’ meaning ear and lith’ meaning stone). These bones help the fish to keeping its balance in the water. When an otolith is removed from a fish, sectioned into thin slices and viewed through a microscope, it reveals a pattern of light and dark concentric rings.

When a fishes’ grow slows in the winter a darker denser ring forms. In the warmer months when a fish is growing faster and a clearer ring is formed. These yearly growth rings are called annuli, which are similar to the rings found in tree stumps. You can count the rings in the otolith or stump and determine age. Unfortunately, for the fish it had to die to allow you to determine its age. Other hard parts in a fish’s body can also be aged in a similar way such as fin rays or scales. Unlike bones, scales in a fish tend to get knocked off or fall off over time and have been proven not to be as reliable as otoliths for aging. Otoliths can be small, thin and clear like in marlins or as large as half your thumb and opaque like the red drum (redfish).

A scientific study called “Age and Growth” allows a fishes’ age to be determined without killing it – except for those used in the initial study. For each species otoliths are collected as soon as possible after they are spawned to as old a fish as can be obtained. Data including the gender and length of the fish are collected along with the information from the otoliths. This information is analyzed for each species and gender and an age assigned for a given range of lengths. While not perfect it’s a good indicator of a fish’s age. A separate analysis is done for males and females because in fish, generally speaking, females grow slower, are larger and are longer lived than males. When you hear or read about a large red snapper or king mackerel being caught it’s a good guess it was female.

When age and growth data are combined with commercial and recreational harvest information, the egg producing capacity of the females (fecundity) and other information the result is called a stock assessment. Stock assessments provide regulating agencies with the data necessary to set angler regulations like length limits, number per day and total harvest. The intent of the regulations is to allow for perpetual renewal of the stock.



Fishy Facts

A three foot-long dolphin fish can be less than one year old.

It’s better to throw the big ones back (females) as they produce more eggs a year than the smaller ones.

Otoliths contain heavy metals like lead and can be used as indexes of pollution.

Otoliths from Indian villages thousands of years old can provide insights into the base level of heavy metals like lead.

Answer 7

how to determine the age of fish

Answer 8

the age of a fish is determined by its scales

Answer 9

the age of a fish is determined by the thichness and colour of its scales.

Answer 10

JUST ASK THE FISH , Hi What is yr age?