Not many veterinarians see fish.  Not many people think about taking their fish to see a veterinarian.  All of this is slowly changing, however.

Aquatic animal medicine is growing field within veterinary medicine.  From koi to crabs to sharks to tetras, all of these underwater creatures have their own set of ailments that veterinarians are learning about and, more importantly, learning how to treat.  At East York Veterinary Center, we are part of the growing number of practices that have embraced practicing aquatic animal medicine.

Fish, like other so-called "exotic" pets, rely heavily on being in a proper environment for good health.  Without good husbandry these animals will suffer from stress, a suppressed immune system, and altered body functions.  All of these changes can either directly cause disease or cause increased susceptibility to other diseases like bacterial infections and parasites.  Therefore, the majority of illnesses that we see in pet fish, corals, or other aquatic invertebrates have to do with things like:

Water quality - this is the MOST IMPORTANT aspect of aquatic animal health.  Parameters like the pH, temperature, salinity, alkalinity, oxygen level, and waste product levels (ammonia, nitrite, nitrate) must be appropriate for fish to thrive.  And not only must they be kept within acceptable ranges, but they must be consistent; sudden or dramatic fluctuations in water quality parameters are likely worse than a level that is consistently a little high or a little low.

Diet - aquatic animals are incredibly diverse...and so is what they eat.  Many fish are instinctively programmed for only a certain diet, like algae or insect larvae, and offering them common fish flakes or pellets may not cut it.  It is best to know what a particular animal eats in the wild and then to try offering that exact same thing, or something as close to it as possible.  Variation is also good when possible; feeding the same brand of the same flake food all the time will mean that  any deficiency the food has will also show up in the fish.

Aquarium design - Some fish like to swim in groups in open water.  Others like to hang out among plants or branches.  Yet others like to hide under things at the bottom.  The point is that if the design of the aquarium prevents an animal from carrying out its normal behaviors and activities, that animal will become stressed and run the risk of becoming sick.  Again, knowing what aquatic animals do and where they live in the wild will allow for accurately designed enclosures that minimize stress and promote good health.

Aggression - fish are like people - some just don't play well with others.  Fighting between tank mates can cause traumatic injury, but can also cause stress that will make the affected animal vulnerable to other diseases and less tolerant of any environmental changes.  Many times, altering the feeding schedule or redecorating/rearranging the tank can help manage aggression.  But other times, only adding or subtracting fish will fix the problem.  The good news is that the temperaments are known for almost all common aquarium fish, meaning the problem of adding an aggressive fish to a "community" tank is avoidable.  

Lighting and water movement - when it comes to corals, these factors are vital.  Corals require the right spectrum and the right intensity of light to survive.  Additionally, the movement of water within the aquarium is very important.  Just as the ocean flows with currents, so to must the water in a tank that contains corals or anemones.  Even with fish, some come from still lakes whereas others come from rushing rivers, so trying to mimic the appropriate water movement will lead to happier, healthier fish.