Many fish prefer sleeping at the bottom of their tank at night, especially those which have been active during the day and require rest periods during their rest cycles. Older fish also seem to enjoy resting there as they become less active.
Fish are known to frequent the bottom of an aquarium to sift through its substrate in search of any food particles that have settled there, often making an appearance at feeding time. Depending on their species, this activity can be quite natural.
Fish that have fallen sick and are lying at the bottom of their aquarium could be suffering from parasites or disease. Carefully observe them, looking out for symptoms like lack of appetite, frantic gills/fins and an overall bloated appearance. In this instance, it would be beneficial to treat with frozen peas which act as natural laxatives as well as aquarium salt and Furan 2.
Another likely explanation for why fish may be laying at the bottom of their aquariums is they feel overwhelmed and stressed due to changes in temperature or overcrowding - or having been transported from a pet store or other source to their new environment.
When this occurs, the best course of action is to reduce the number of fish in your aquarium and ensure those left are compatible with each other. Furthermore, try rotating its decor every few weeks to create an engaging and stimulating environment for your fish to enjoy.
