The primary reason most freshwater aquarium fish die is poor water quality.  The main causes of poor water quality are:

• Uncycled tank
• Insufficient filtration
• Insufficient water changes
• Insufficient removal of fish waste
• Too many fish for the size tank
• Contamination

Many people who are new to aquariums don’t understand how to identify water quality problems.  The three most important water parameters for freshwater aquariums are

• Level of ammonia
• Level of nitrite
• Level of nitrate

Ammonia, nitrite and nitrate are nitrogen-based compounds that are produced by fish in the form of waste, but also by decomposing food, etc.  The best way to test the levels of these compounds is by using a master test kit, found at most aquarium stores.

Non-zero levels of ammonia and nitrite are indications of New Tank Syndrome, also called a cycling tank.  See the New Tank Syndrome section below.

Elevated levels of nitrate (>40-60ppm) is caused by Old Tank Syndrome, discussed below.

Symptoms Of Water Quality Problems

The major problem with water quality problems is that fish don’t recognizably die directly from poor water quality.  They die from opportunistic diseases that take advantage of a weakened fish, such as:

• dropsy
• internal parasites
• bacterial infections
• fungal infections
• etc

New Tank Syndrome

“New Tank Syndrome” is the common name given when fish become ill or die in a newly establish aquarium.  Fish naturally produce ammonia as a waste product.  Excess fish food will rot and produce ammonia as well.  Aquariums containing fish need to establish a “cycle”, which is basically colonies of bacteria in the aquarium that process fish waste from poisonous ammonia and nitrite to less harmful nitrate.  Please see the page on cycling aquariums for more information.  In new tanks, tanks that have had the biological filter damaged or destroyed, or tanks that suddenly were overfed or had a big increase in fish, ammonia and nitrites will build up.  These compounds are quite poisonous to fish, and a build up of either or both ammonia and nitrite generally results in sick or dying fish.

If you suspect new tank syndrome, because the tank is new, a large amount of food was recently introduced, or many new fish were introduced, follow these steps:

1. Stop feeding the tank.  Continuing to feed will make the problem worse.  Most fish can easily go several days without eating.
2. Test the water parameters with a master test kit.  If none are available, take a sample of water to a local aquarium store, and they will generally test it for free.  This isn’t ideal, as many stores use unreliable “test strips”, but it should be accurate enough to show whether or not this is the problem.
3. Perform partial water changes until the ammonia and nitrite levels get to zero and stay there.  The aggressiveness of the changes really depends on the level of ammonia or nitrites.  The higher the level, the more frequent and large the water changes need to be.  At 1 to 2ppm, change 50% of the water daily.  Above that, change 60% to 70% twice daily.

Old Tank Syndrome

Old tank syndrome happens in cycled tanks with well functioning bio-filters.  Over time, ammonia and nitrite are consumed by bacteria to produce nitrates.  Nitrates are far less toxic to fish than ammonia and nitrite, but in high concentrations, it will sicken or kill fish.  Unless some action is taken to reduce the concentration of nitrates, eventually old tank syndrome will set in and result in dead fish.

Old tank syndrome can be avoided with these precautions:

1. Perform periodic water changes.  commonly 20% to 50% weekly, depending on the number of fish, amount fed, etc.  The target level for nitrates should be under 20ppm.  Using a master test kit and some experimentation will help you determine the right frequency and volume of water changes for your tank.
2. Don’t overfeed fish.  If you see excess food laying on the bottom of the tank after feeding, you are most likely feeding too much.
3. Vacuum the gravel periodically.  In tanks that have sand or gravel, over time fish waste and excess food get trapped and the decomposition process can become a serious problem for the level of nitrates.

If you suspect old tank syndrome, follow these steps:

1. As with above, stop feeding the tank.  Continuing to feed will make the problem worse.
2. Test the water parameters with a master test kit.  If none are available, take a sample of water to a local aquarium store, and they will generally test it for free.  This isn’t ideal, as many stores use unreliable “test strips”, but it should be accurate enough to show whether or not this is the problem.
3. Perform partial water changes until the nitrate levels get below 20ppm.  The aggressiveness of the changes really depends on the level of nitrates in the tank.  The higher the level, the more frequent and large the water changes need to be.

Treating Illness with Medication

Many fish-keepers will attempt to treat the apparent disease with antibiotic, anti-parasite or anti-bacterial medications, but not the underlying cause – water quality.  Indeed, particularly in the US where antibiotics are readily available, many new-comers make a bad situation much worse by treating a tank with medication that kills off the colony of beneficial bacteria, leaving the tank uncycled.

It has been my experience that, in nearly all cases, fish that are showing obvious signs of illness will not survive despite best efforts and intentions.  To be sure, there are many astute and experienced fish-keepers who can nurse a sick fish back to health, but such experienced people also know that prevention is far more effective than a cure.

Good Practices For Maintaining Fish Health

Filtration

Ensure the aquarium has the proper amount of filtration.   While there are a number of variables, such as volume of water, number and types of fish, amount of food used to consider, the general rule of thumb is to size the filter to pump the water between 5 and 10 times per hour.  For example, a 55G aquarium needs filters that will pump between 275 and 550 gallons per hour.  My strong recommendation is to purchase two smaller filters whose flow rate adds up to 10 times the volume of the tank.  The That might seem excessive, but it does ensure good filtration and provides some ability to ride out the failure of one filter.

Using a UV filter is also a very good way of eliminating opportunistic microorganisms in the aquarium.

Water Changes

As with sizing filters, there is are a lot of variables that go into how much and how often to perform water changes.  Internet forums are full of recommendations… from 20% per month to 20% per week.  There is a sizable contingent of well intentioned people who insist that anything more than 20% per week is harmful to the fish.  I do not subscribe to that way of thinking – fish will not suffer from having too much clean water.  I perform 50% changes weekly on my tanks with good results.  It’s a lot of work, but the Python makes it manageable.

Removal of Fish Waste

Some fish waste is dissolved or suspended in the water and is removed through water changes.  However, far more of it hangs around in the form of poop at the bottom of the tank.  Tanks that have gravel on the bottom make this situation hard to see, and without a thorough cleaning of that gravel, bad things can begin to happen, even if the other suggestions are followed.  First, I would strongly recommend most people to skip the gravel, unless there is a particular need.  Spend the money on pieces of drift wood or similar things to cover the bottom.  These can be moved around when it comes time to clean.  Regardless, the fish waste needs to be pulled out weekly as part of the water changes.  A gravel vacuum, like the Python, can clean both bare bottom and gravel bottom tanks.  Bare bottom tanks have a distinct advantage in that it’s easy to see the waste and see that it has all been sucked out.  In gravel tanks, a thorough cleaning of all the gravel is needed to ensure getting most of the waste.

Too Many Fish

Again, there is not a 100% reliable method of determining a safe number of fish for a tank.  The rule of thumb often quoted for freshwater fish is 1 inch of fish (at it’s adult size) per gallon of water.  This breaks down, however, with large fish like goldfish, oscars, etc.  Fish that are packed in to an over stocked tank are very likely to contract a serious infection and die due to the combination of a compromised immune system from stress.

Proper Tank Size

Determining the right size aquarium for the fish you are keeping is as much an art as it is a science.  Fish that grow large, such as goldfish, koi, knife fish, etc, will experience similar symptoms to those when a tank is stocked with too many fish.

Getting Immediate Help For Your Specific Problem

There are several great forums on the Internet that have emergency fish help sections where questions are generally answered in minutes by very knowledgeable, friendly and caring people.  Two such forums are here:

• FishForums.com Tropical Fish Emergencies – read this before posting
• AquariaCentral.com Freshwater Illness and Disease – read this before posting

If you are lost on how to proceed, or need validation on what you are doing, I strongly encourage you to post a message on one of those forums.  Be sure to read the link labeled “read this before posting” for which ever forum you visit.  Following that forums instructions on information to include in your post will make helping you much faster and easier.

Post from: Tropical Fish Central

Why Do My Fish Keep Dying?

Yesterday was my day for weekly aquarium maintenance.  I had drained one of my 55G tanks down about half way and noticed that my Rena XP 2 filter was barely trickling out.  I keep the filter in a decorative box next to the tank, so I unplugged the filter, disconnect the input/output hoses, and take the filter to my sink.  In the process of disconnecting the hoses, I had to wrestle with it a bit, because of the angle that the hoses come through a hole in the back of the box.  This is important.

I cleaned the filter, hooked it back up, and saw that it was pumping a good flow again.  Satisfied, I closed the box, and went to dinner with my family, who have been staying with us for the holiday, at Macaroni Grill.

I was looking forward to getting to bed when we got home.  I walked in the door, played with the kids for a few minutes and heard a sound that didn’t sit right.  I heard the sound of a filter spewing water above the water line of the tank.  I ran into the family room and my heart sank when I saw that the water line in the 55G tank was about 2 inches below the black plastic rim at the top.  I opened the box, and sure enough, there was a puddle in the bottom.  Conveniently, the box has holes in the bottom, meaning that about 5 gallons of water had been released into the carpet below.  At first, I thought I didn’t seal the filter head or the hose assembly properly.  I reseated both, and the water kept coming.  I started mopping up my mess; my wife giving me the look of disapproval the whole time.  Finally, after a few minutes of drying the hoses off, I noticed that the water was leaking between the hose and the hose barb.  Apparently, when I was wrestling with the hoses to get the hose disconnect off the filter, I stretched the hose out and it did not seal around the barb any longer.  Being about 2 years old, the hose was apparently not as elastic as it was when new.  Nothing I did to push the hose onto the barb helped.  So, I was off to Home Depot for some hose clamps.  30 minutes later, I was hose clamping the crap out of all my filter connections.

Back to the carpet for a minute.  When a lot of water is unleashed into carpet in a fairly small area, the water does something that is quite similar to underground streams in nature.  Sure, the area under the filter box was soaked, but there were several spots, up to about 8 feet away, where puddles had formed and soaked through to the surface of the carpet.  These spots are maddening.  I would lay out towels on the spot, step on the towels to soak of the water, and repeat about 7,000 times for that spot.  It would seem dry, then I would move on to the next spot.  Once I was done with the next one, I would notice that the first spot is back to soaked again: the under-carpet aquifer in action.  I fought the torrent until I ran out of towels.  And with my wife being a professional shopper, we have a lot of towels.  I set up a fan to blow across the carpet.  That fan has been running for nearly 24 hours now, and the carpet is still pretty damp.

So, the lessons are:

1. Use hose clamps on fittings when running hoses for filters and the like
2. Inspect the filter 5 to 10 minutes after performing maintenance to check for leaks that you may have missed or were too slow to have made a noticeable puddle

The second lesson is particularly painful for me.  About a year ago, I did something very similar – I have a 125G tank in my bedroom with several XP filters in the cabinet below the tank.  After cleaning a filter, I reconnected everything and went about my business.  Went to bed, got up, went to work, etc.  I got a call from my wife about lunch time the next day saying that the carpet around the tank was wet.  I was able to talk her through finding the offending filter and fixing it.  I suspect about 15 to 20 gallons got out in that nightmare.  That was also my first experience with the dynamics of under-carpet water flows.  But, after that incident, I told myself that I would always go back and check a few minutes after filter maintenance.  I did it religiously for several months.  I never found a problem, and eventually I stopped doing it.  This is one of those things that you must do, every time.

Post from: Tropical Fish Central

Disaster Strikes… A Leaking Fitting On An External Filter Causes An Under-Carpet River