Treating Diseases? Why Not Just Don’t Get Them In The First Place?

Or... how to keep your fish disease-free.

Everyone gets diseases. It’s part of the learning curve, especially in the early years. All the available information out there about all the different diseases, can be very worrisome to a beginner, and fishkeeping can seem like a precarious life or death kind of hobby that we have little or no control over. Most fishkeepers think a disease can strike at any time.

This is incorrect.

Disclaimer... I am far from being a disease expert, but I have learnt over the years that keeping fish free of stress means they will never catch a disease. I had the added advantage of being told this by the guru I met right at the start when I was 10.

Fish can arrive with diseases and/or parasites of course, but in a healthy tank, if a disease appears it’s nearly always because we have done something wrong.

The list of things that can stress a fish is a long one, but I’ll list the main ones.


WRONG WATER

Hard water fish need hard water to be stress-free. Soft water fish need soft water. Some even need blackwater with a very low pH to be stress-free.

Most freshwater fish need salt-free water to be stress-free. Salt prevents a lot of diseases, but stress-free fish don’t need it.

Water movement is also important. Don’t keep powerful, high oxygen using fish from fast flowing streams in low flow water, and don’t keep weak swimming fish from the swamps in a fast flow.

BAD WATER

An efficient filter means never any measurable ammonia or nitrite (the only way to stress-free fish). Always dechlorinate to remove chlorine and metals. Ensure good aeration at the surface.

NOT ENOUGH WATER CHANGED

Water changes remove nitrate, phosphate, growth inhibitors produced by the fish, and presumably a host of other things. I’m no chemist either. They also replenish minerals such as carbonates and trace elements used by fish, plants and bacteria.

Re the nitrate debate, different species have different tolerances, but it is true to say that for all species, the lower the better.

It’s impossible to change too much water if the water is good and it’s parameters (eg hardness, temperature) are similar. And it’s dechlorinated of course.

And every water change is beneficial. Appetite and growth rate are both dictated by water changes. In a river, fish get a constant water change.

WRONG TANKMATES

A few notes...

Some fish are territorial. Cichlids should be given the size of territory they want. Then they’ll be peaceful. A lot of fish also defend a feeding territory.

Be careful with nocturnal fish, as they can prevent diurnal fish from getting a good nights sleep. Especially if they’re very active, or bulldozing the sleeping fish out of the way.

Big fish tend to be kept very overstocked. This often just causes constant stress.

If any fish is being routinely chased or threatened (including cichlids) they need to be separated asap. Prolonged aggression is not a natural situation and is just causing stress and heading for disease. In nature they just run away.

WRONG NUMBERS

If a fish “should be kept in a group” keep it in a group!!! At least 6. I’d love to say at least 12. The more the better. We tend to keep 6 of these, 6 of those... this isn’t ideal. One 12 is less stressed than two 6’s. All shoaling fish are less stressed in bigger numbers.

STOCKING

The nearer you get to the ‘stocking limit’, the more stress there’s likely to be. Don’t go there. Most fish need some degree of ‘personal space’, even some shoaling species. They can feel crowded. It’s not about ‘filling the tank’ with fish. Fish in general are less stressed with fewer tankmates and more space. The smaller bioload also makes the tank easier to maintain.

SUITABLE DECOR

Try to make the tank resemble the natural environment of the fish. Whatever the fish does in nature, let it do in the tank. If it hides in the bushes give it bushes to hide in. Do this for all livebearers. If it sifts the sand for food, give it areas of sand and not gravel. If it lives near the surface it will probably want shade from bright lights.

Give nocturnal fish enough places to stay comfortable in darkness when the lights are on.

DIET

 A variety of species-suitable foods is required. The better dried foods are excellent but herbivores and carnivores need different diets. Frozen and live foods are also beneficial. Most herbivorous plecs also need softish wood.

It’s easy to overfeed, but most fish eat every day except those ie predators that eat large meals. Herbivores eat little and often.

LIGHT

Fish do not like bright lights. If lights are bright, provide shade. If a fish lives near the surface but not out in open water, it wants shade as an option.

Most also don’t like white sand/gravel. Stress-free to most fish means a darkish substrate. It’s why fish have darker backs than bellies. Camouflage from above. Most fish will change colour to try to match whatever substrate they’re on, as much as their colour repertoire will allow. If they can’t get a match and become less noticeable they’ll be stressed.


This list is by no means exhaustive, and it’s still in the “bit of a ramble, could do better” stage. I’ve missed out... vibrations from people stepping on that floorboard as they walk past, and plenty more things that can stress fish. Tapping on the glass...

The bottom line is, diseases can be all about prevention rather than cure. Keep your fish the way THEY want to be kept, rather than the way you want to keep them, and they won’t get diseases.