Zebra danios start out tiny and grow to a length of about one to two inches. Their lifespan typically lasts for two to three years.
While it can be difficult to determine the exact age of a zebra danio, there are some general indicators you can look for:
* Size: As mentioned, zebra danios typically grow to a length of about one to two inches. As they age, they will gradually increase in size.
* Color: The coloration of a zebra danio can also give clues to its age. Younger zebra danios tend to have brighter, more vibrant stripes. As they age, their stripes may become duller and less distinct.
* Behavior: Young zebra danios are typically more active and playful. As they age, they may become less active and more sedentary.
* Lifespan: The average lifespan of a zebra danio is two to three years. If your zebra danio is older than this, it is considered to be a "senior" fish.
It's important to remember that these are just general guidelines. There can be some variation between individual zebra danios.