The zander is one of the top predators of the lake
The zander prefer to live in lakes that are quite big and quite murky. It is very sensitive to light and therefore it seeks to live and hunt in places with low light conditions during the day. It is a very night active fish that prefers to hunt in the dark hours. The murky lakes are often lakes with high nutritional value and lots of plankton algae. Algae makes the water murky and makes it difficult for light to penetrate the deeper parts. The amount of algae can also be too high. If it is too high, the oxygen levels will be low during the summer and this is not preferred for the zander, since it is very sensitive to this. The zander need high levels of oxygen to thrive.
It can also thrive in clear waters, but if so, it prefers to be in lakes that are quite deep and provide the zander with the possibility to disappear from the light hours during the day. The zander can also be abundant in slow flowing river, such as deltas. Often, the water is quite murky in these waters, which means that the zander loves to hunt here.
The zander likes warm water. Their optimal temperature for growth is between 24-29 degrees Celsius. If the temperature drops to under 8 degrees Celsius, the growth process stops. The zander is known to survive at temperatures all the way up to 35 degrees Celsius.
It can also survive in brackish water with salinity reaching 12 ‰. Research shows that the zander grows faster in water with a bit of saltwater and it can survive short time in salinity levels reaching up to 25-30‰. The bigger zanders are more adaptable to higher levels of saltwater.
Age and size
The size is more essential to the sexual maturity of the zander then age. The male is sexually matured from around 25-35cm, but the female must wait until 25-45cm of length before it is ready to spawn. It normally takes around 2-5 year for them to reach this length. In lakes with slow growth, it can up to 10 years to reach maturity. As described above, the growth is in very close relation to the temperature. It is of course also dependent on the food available to the zander. So, the further south, the better conditions are there for growth potential.
The best growth conditions are found in Russia, where the warm mainland provides as steady warm temperature for the zander to grow. Normally the zander lives until 12-15 years of age, but in some cases, they have been found to live more than 20 years and the record is 24 years.
The zander is one of the top predators of the lake
The zander spawns in the springtime, depending on the temperature that must be between 8-16 degrees Celsius. They spawn in low water where the lake bed consists of small gravel. The male will dig a small hole, by using its tail to remove the gravel. They aim for the hole to be 50 cm in diameter and 5-10 cm deep. The best is when there are small branches that the eggs can get attached to. The best spots are often limited, so there are gatherings of many males, trying to find the best place to put make the new generation.
After the hole has been dug, the female announces her arrival and the spawning begins. The spawning always starts out with 20-25min of foreplay and then she lays her eggs and the male will fertilize them.
When the female is done laying eggs, it would have laid up to 2 million eggs. It can vary from 150.000 to 400.000 eggs pr. kilo zander. It will take around 3-8 days for the eggs to hatch, with the right temperature.
What does the zander feed on?
When the zander starts of its life, it will live of its yolk sac in the beginning, but it will already be gone in only 2-3 days and after that the zander larvae are dependent on finding food on its own. Low temperatures can make it hard for the larvae to find something edible and survival rate will go down dramatically. After a few weeks, they will have grown so much that they can start to eat daphnia and water fleas. The Zander is very much a predator, so when it is around 20mm it can prey on small fish fry, such as perch, roaches, bleak or other species it can swallow.
When the zander reaches 10cm, it will dominantly eat fish as a diet. The only exception is zander that lives in brackish waters. They live of shrimp and fleas until they grow too big for that.
As many other predatory fish, the zander will swallow its prey whole. It cannot swallow anything bigger than 1/3 of its body length. Its diet in lakes mainly consists of perch, roach, ruffe and smelt. In rivers, it is mostly roach and smelt. When you get into saltwater or brackish water, the diet is mostly herring or sprat.
An active hunter
The zander is a pelagic fish that hunts in the open waters of the lakes. It does also search for food near vegetation or close to the bottom. It is a true hunter that catches up to the prey, when it starts to escape. When it catches the prey, it can eat it in 2 ways. If the prey is small, it will swallow it whole and often with the tail first. If the prey is a bit bigger, it will try to grab the prey in the middle of the body and then turn the fish around to swallow it head first. Fish with spikes, like perch will always be swallowed head first, so the spikes does not get stuck in the throat of the fish.
Night active. The zander is now found of light, so during the day, it seeks towards deep or darker parts of the lake.