Appetite: Eating food quickly.
Breathing : Regular breathing (normal respiration).
Behavior : Active, alert and sociable
Eyes are bright and clear
Fins: No tears, splits, spots or bleeding veins.
Fins should also be held away from the body, not folded.
Movement : Swimming freely and evenly
Scales: No sign of injury or bacterial / fungal growth
Researchers are investigating how fish sleep. They have found that fish do not go through the same sleep patterns as land mammals, but instead rest in a number of different ways. Some fish float in place, some wedge themselves into a secure spot in the mud or coral, and some even locate a suitable nest. These periods of "suspended animation" may perform the same restorative functions as sleep does in people. Fish ’sleep’ has an area of active research today; while there is no consensus as to what level of consciousness fish experience while they are sleeping there is strong evidence that they reduce their activity and metabolism while remaining alert to danger."
Cycling is the process of establishing a population of living bacteria within an aquarium. Housed on the filter media, substrate, and surfaces inside the aquarium, bacteria biologically filter the water as they carry out their normal life functions. Collectively referred to as a biofilter, the bacterial colonies should be well-established before introducing animals into the aquarium, or survival is unlikely. This can take several months or even years for certain conditions to develop if you are prepared for initial failure after adding fish or plants. Most tropical fish will tolerate just about any ammonia level provided there is adequate room for plant growth before it reaches potentially dangerous levels.