Is it normal for my dalmatian molly to be chasing in 20 gallon tank aggresively after just introduced the are young still and as they grow I am moving them a new tank?

Dalmatian mollies are social fish that enjoy living in groups, and they are known to be territorial. When you introduce new fish to a tank with existing dalmatian mollies, it is normal for the dalmatian mollies to chase the new fish as they establish their territory. This behavior is usually temporary and will subside as the new fish settle into the tank.

However, if the dalmatian mollies are continuing to chase the new fish aggressively, it may be a sign that the tank is overcrowded. Dalmatian mollies need a minimum of 15 gallons of water per fish, and more space is required if there are other fish in the tank. If you are planning on moving the dalmatian mollies to a new tank as they grow, it is important to make sure that the new tank is large enough to accommodate all of the fish comfortably.

In addition to overcrowding, there are a few other factors that can cause dalmatian mollies to become aggressive, including:

* Water quality: Poor water quality can stress dalmatian mollies and make them more likely to become aggressive. Make sure to keep the water in your tank clean and free of harmful chemicals.

* Lack of hiding places: Dalmatian mollies need places to hide in order to feel safe. Provide plenty of hiding places in your tank, such as plants, rocks, and driftwood.

* Competition for food: Dalmatian mollies are opportunistic eaters and will compete for food with other fish in the tank. Make sure to feed your fish regularly and in amounts that they can all finish in a few minutes.

If you are concerned about the aggression of your dalmatian mollies, it is important to take steps to address the underlying cause. By providing your fish with a suitable environment, you can help them to live long, healthy, and happy lives.