Sometimes by just doing some simple observations, you can learn a great deal and knowledge and probably your fast action would have saved the life of your fish. There are several signs and condition listed below which you can use to determine whether something is not right with your pet.
Among the Symptoms of Sick Fish are:
2) Unusual movement and activity– Does it swim in an erratic manner? Flashing and scratching on aquarium surface? Does the fish find it hard to maintain balance in the water?
3) Acceptance of food – Not eating and with reduced appetite leading to weight loss.
4) Fish color – Usually you will find fading in the color of your sick fish. For certain fish like neon fish, the color could become light and pale while other species like discus, it will instead turn black overall on the whole body and you will know it’s already sick
5) Breathing right below the water surface – this is a common symptom, which might be telling you that the water condition is poor. Usually high level of nitrate (about 300 ppm) will cause this symptom. (Read more on Nitrogen Cycle)
6) Clamped fins – The fins are not stretched out and wide open, as it normally will.
7) Other symptoms – appearance of tiny white spots (ich), holes in the head, pop-eye, raised scales, open wounds on the body, red veins on the fins, cotton like material on the gills, rotting fins
Finally, as a responsible pet owners, not only should you ensure that the living condition such as water quality is alright but you must also took the effort to learn about common types of aquarium fish disease like ich, fungus infection, dropsy, mouth and fin rot and knowing some of the basic fish medication.