Priciples of fish tank aquariums

I consider an aquarium furniture, so having a beautiful piece of furniture that needs little maintenance is the key.  A properly set up fishtank aquarium relies on four easily learned principles.  Knowing these four principles will allow you to have a beautiful set up that is self sustaining requiring limited maintenance.  These four principles aresufficient oxygen, the proper temperature, the proper light, and correct feeding.

Like land animal’s fish also need oxygen.  They of course get along on much less than a regular warm blooded land animal, by absorbing dissolved oxygen from water as it passes through their gills which are equivalent to lungs for us.  As fish use up the oxygen in the water they live in, the water absorbs more oxygen from mainly its air to water surface area.  Cooler water absorbs more oxygen than warmer water.  The larger the air surface the faster the water can replenish oxygen.  The water surface area at the top of an aquarium is the main way that oxygen enters the water in it.  This is an important factor to keep in mind as any aquarium can only sustain a certain number of fish because of its surface capacity.  Depth of water or cubic capacity does not factor into how many fish can reasonably be held in an aquarium.  Two other ways oxygen can be absorbed into aquarium water are through live plants under the influence of favorable lighting, and artificial aeration.

The wisest principle is to only keep the number of fish in a fishtank that the air surface per fish ratio is relied on as the factor that limits the number, rather than adding in the other two ways to improve oxygen absorption.  Allow 3 square inches per fish to accommodate a fish the size of a full grown guppy.   Larger fish such as full grown sword tails should have 8 square inches per grown adult fish.  Larger fish such as barbs or Cichlids require 54 square inches of surface area.  With aeration you can have more fish but you run the risk of overcrowding if the air pump fails.

fish tank surface area vs depth

Aeration is a standard practice for most fishtank aquariums where a small electric pump pressurizes air causing it to flow through a tube running to release head creating bubbles that rise to the surface.  It is mistakenly thought that these bubbles absorb into the water.  Rather the bubbles disturb the air surface at the top of the aquarium and actually make it a larger area as well as circulating the oxygen through out the water improving the absorption rate and keeping the oxygen level higher than it otherwise would be.  Aeration should always be left running at night in aquariums because plants give off carbon dioxide and make no oxygen at that time.   A stream of air running through the aquarium effectively doubles the fish capacity of an aquarium.

The only disadvantage if any to aeration is that if it is used continuously, the fish will become dependent on it. If a power failure occurs or for some other reason the pump is shut off the fish go through a withdrawal phase that causes stress to them.   A small stream of fine air bubbles seems to perform better than larger bubbles.

Along with aeration I will mention that plants help in oxygenating the water when they are put under the correct lighting.  Not only do they oxygenate the water but they also absorb carbon dioxide which the fish give off in breathing.  To top it off they also absorb accumulations of fish waste and anything else settling into the gravel at the bottom of your aquarium.  They do this through their root system.  Other obvious benefits of having real plants in the aquarium are the look they create and places for fish to hide.  Plants create a small eco system between themselves and the fish to the advantage of both.

The amount of light an aquarium requires is dependent on if you plan on using real plants.  If you have no intention of utilizing real plants then the problem of lighting is simplified along with the location of your aquarium.  All you need is a place where the temperature isn’t changing a lot and where there is enough light for the fish to see their way about the aquarium.   Do not add real plants to an aquarium later on if you change your mind unless you add artificial lighting or change the location.  Remember plants will give off unwanted gases in dark areas.

For most plants you should strive to keep a medium amount of light.  Near a window where diffused light is available should be kept to approximately 2 hours of direct sun light.  Make sure you have a method of controlling the amount of sunlight through a system of blinds or curtains.   The biggest problem that occurs with too much light is the over growth of algae, creating green water and or green moss on the plants and rocks as well as the glass.   The idea is to stimulate the plants into the oxygenation action, yet not create the unwanted algae.  Artificial fish tank light has the great advantage of total control.

For artificial light to stimulate plants it must be very close and overhead.  Usually they are housed in the canopy or hood of the aquarium.  A rough estimate of the amount of light needed on a daily basis is a 10 gal. tank 40 watts for 8 hrs.  or 75 watts for 4 hours.

For 15 – 25 gal tanks 60 watts for 7 hrs.  For larger tanks 75 watts for 9 hrs. Reduce these times if you have some diffused sunlight.  Make sure you get bulbs that are clear and give off the correct wave length for stimulating plants.  Plants are stimulated by the red end of the spectrum.  Depending on your location the only other factor that you should take into consideration with artificial light is the heating effect.  On hot summer days the lights can heat the water above the desired temperature.  Raising the lighting further away may be necessary to stop the temperature rise.

Temperature is the last of the principles we will discuss.  Tropical fish by and large can live in water temperature between 70 – 80 degrees.  Some species prefer the lower end and some the higher end, but most can tolerate a swing of 5 degrees over a period of several hours.  Don’t get too bogged down with trying to keep your aquarium with in a two degree range.  Mother Nature doesn’t do it so why should you.  We can boil all this temperature information down to a few simple rules.  Keep your aquarium in and around 72 -76 degrees.  For short stretches the temperature can go down to 67 degrees and up to 85 with out problems.  It is of course preferred to keep the temperature in the 70’s.  If you suffer a power failure and the temperature has dropped below 67 you can still overcome this difficulty by slowly raising the temperature to 80 and keep it there for 30 hours to allow the fish to recuperate.  Do not for any reason remove a fish from one aquarium to another with a net, even if the aquariums both seem to be the same temperature.  Thermometers have been known to be off by up to 4 degrees.  This can cause stress on fish and create the shakes or worst yet ick.  Either way you most likely have a dead fish on your hands.  Always take some water from one aquarium, put it in a plastic bag and float the fish on top of the new aquarium it will enter for at least a half hour so the water in the bag equalizes to the new aquarium.

Feeding of fish is the fourth principle and probably the one single principle that people err on.   Fish are sensitive to temperature and eat more if they are near the top end of their living temperature range.  At 68 degrees the water is cold and they will not likely feed.

When the water is in the low 70’s range they will feed decently, and in the high 70’s range they will feed ravenously.  Water higher than 80 will not create any increased feeding due to the water aeration starting to drop.  Remember colder water absorbs oxygen easier than warmer water.  Digestion and appetite are linked together, both needing oxygen and a good temperature for the fish to thrive in.

Monitor your water temperature and feed as follows;

Once a day for water in the high 60’s – low 70’s, and twice a day for temperatures in the 73 to 80 range.

If you are feeding dry flake food it is best to introduce small amounts over a 10 or 20 minute period.  This way you will watch the food disappear and know the fish have fed well.  Remove an excess food if the fish stop feeding and never give any more than a small pinch at a time.   It is best to feed in the morning if possible particularly if you have plants because the oxygen level will rise in the tank and aids in digestion.

If you are going to be away for a few days and not able to feed the fish it is not a great worry to just leave them unfed.  They will not starve.  I recommend turning your heater down to 70 degrees just to help curb their appetite.  If you are going on a longer trip or holiday you will need to bring in a substitute feeder.  Make sure you train them in how to feed and removing the excess food.  A great idea I use is to put the correct amount of dry flake food in a small packet envelope for each feed and instruct the feeder to only use one per day.

There are alternatives to using dry flake food.  You can feed fish live food as well but be careful how many mosquito larvae or Daphnia you introduce as you don’t want leftovers of live food hanging around.  Mosquito larvae do turn into full mosquitoes in short order and then they are in your house.

Freeze dried brine shrimp or tubiflex worms and daphnia, as well as many others are readily available from your local aquarium store.

Remember proper feeding is a core principle of creating a self sustaining clean environment, so take care to do this right and you will achieve a balanced in your fish tank aquariums.

I’ll go into types of food and feeding much more in depth later on.