4 min read

The Three Rules of Fishkeeping

Written by Russell McAndrews

It really should be the 3 million rules of fish keeping but I can’t remember that many. Besides, these three rules encompass all the others, (I think?). One could spend a lifetime enthusiastically studying fishes and only scratch the surface. In fact, what one would have learned is the fantastic scope of one’s own ignorance. There’s a phrase that I’m fond of “You don’t know what you don’t know”. It will mean different things to different people and different thin to the same person at different time? How can anyone know what they don’t know. One can make assumptions, guesses, do research, experiment and observe. The trouble is, although this seems to make perfect sense, in reality it doesn’t work and this is why. Bear with me as I pull a number out of thin air, but say every answer uncovers 3(?) more questions and so on and so. It feels like going backwards. You start with what you may think is a firm mental grasp and are lucky if you can maintain any grip at all. But I digress.

Rule #1 - FISH JUMP

I say number one not because it is the most important but because it is the easiest to forget. Fish jump! Intuition fails us on this one. We don’t expect them to jump out, but they do. Many of you out there probably already know this but they are actually quite talented jumpers. Some are better than others but they are almost all very capable. Seahorses are perhaps an exception.

Fish jump for the most astounding and unbelievable reasons. None jump better than Killifish, they can hit the smallest opening. There are Killifish that “bask” out of water. There are perch that climb trees. There are fishes that lay their eggs out of the water. Then there are “mud skippers” they can do all that.
Of course, fish primarily jump to avoid a pursuer. That would include us to take care when entering their world or they may injure themselves. Its my belief that 90% of jumps happen at the corners of a rectangular tank. They follow one vertical surface until they encounter the other then go up!


That’s what they do! It is perfectly natural behavior and I think most of us expect that, even if they surprise us.

Again some fish are unbelievably accomplished at eating other fish. In fact, many varieties have been known to bite off more than they can chew, or more importantly, swallow! By way of one example they will try to east something so large that they choke to death, killing themselves as well as their meal.

Rule #3 - FISH DIE

Rule number three speaks to the previous two rules, it represents an underlying theme. It would be silly (I think) to talk about capability in this context, but just know that some are more capable than others. I think its also relevant to remind everyone that everything dies. Even if absolutely nothing goes wrong everything still dies. Obviously we want to delay this behavior as long as possible. There are so many ways for fish to die its hard to begin. Forty six years of fish keeping experience did not come without cost. Its not something I’m proud of, but I think most of you would understand me if I were to say, “I’ve killed more fish than most people have seen”. I’ve deliberately used the word killed because those which died of old age we could do nothing about. In fact, they are the success stories. I’m debating with myself at this point as to how best to organize (so as to then present) these casualties. Should we separate the “preventable ones” vs. the “unpreventable ones”. No that won’t work when it comes right down to it they are all preventable. One can’t segregate the accidents because they’re all accidents, I hope (Oops I’ve neglected to consider feeders).

I’ve got it, let's organize by size. We’ll begin with the “fish room wipe out”, the “tank wipe out” and so on down to the individual. There may be some overlap or even some commonalities and we might have to jump around a bit but I can think of no better outline.

When an entire fish room dies it is usually some off-site, environmental factor that is responsible, a lengthy loss of utilities (heat, power, water, etc.). Sometimes a local disaster I.e., flood, death of the keeper, etc. Unfortunately sometimes it’s a pathogen which sweeps through the room or part of the room. This is entirely preventable if one can adhere to strict quarantine (I don’t and have had this happen).

When an entire tank dies the most likely cause (in descending order) is the heater, over cleaning the filter or overfeeding.

Heaters fail “on” or “off”. The thermostatic contact points, overtime, can weld themselves shut bypassing the thermostat and cooking the tank. The fish may dart about skittishly or gasp at the surface. Acrylic insulates better and so will cook faster.

Over cleaning is physiologically a very stressful event for a fish. Many people remove the fish from the tank, this is usually a mistake. Over cleaning the filter(s) is ecologically stressful. Effectively switching off the biological filter will result in lethal spikes of Ammonia. Ammonia stresses fish. In alkaline water Ammonia kills fish.

Filters can become “clogged”. No flow equals no filtration. Detached airlines, unplugged motors, loss of prime of jammed/broken impellers will all disable the filter. Again, no filter means Ammonia.
Overfeed produces, you guessed it, Ammonia. Uneaten food will itself produce Ammonia directly. The concentration of Ammonia in the water may overload the filers capabilities and will stress or kill. When individuals die it is usually murder!

Oh yeah, a dead fish will kill as well.