How To Effectively Deal With Pond Fish Problems

A sick pond fish, no matter what kind it is (koi, goldfish, etc) is one of the most disconcerting things that a pond owner will run into.  It’s stressful, worrysome, and can make any fish-loving person have some sleepless nights.  

For some fish ailments, there isn’t always a simple and easy answer to remedy everything, however we’ll try to break down some proactive steps you can take to improve the situation for your fish and perhaps bring them back to good health and vitality.  In a sense this is a useful step by step checklist that you can use anytime you run into problems.

Obviously when you first notice problems you’ll want to review several things and ask some basic questions with an attempt to narrow down the possibilities of what’s really going on with the fish.  Is it a widespread issue or is an individual fish affected?  What are the symptoms?  What’s changed in the pond environment?  And if we want to cover, at least at a baseline level, the main culprit in most fish illnesses we would need to ask ourselves one simple question (albeit, there are a variety of answers) and that is “what is it that might be causing stress to the fish?” Finding the answer to that question will often provide clues to the root cause of whatever your fish may be dealing with.

Why is the source of stress our primary focus?  Well, according to a number of veterinarians and experts on fish health, stress, regardless of the source, can often hinder the immune system of a fish and make it very susceptible to any number of ailments or diseases.  Along with other things like water quality problems in the pond, or injuries and poor nutrition, each component can add up to problems for any kind of pond fish.

Diagnosing The Possible Source Of Stress

Here’s a few things to check to help narrow down what may be causing your fish health issues or could be a main source of stress.

  • Have the fish been handled or transported recently?
  • Are the fish experiencing seasonal changes?  (mainly coming out of winter)
  • Are fish over or underfed?
  • Have you tested the pond water for ammonia levels? (ammonia test strips)
  • Have you tested the pond water for high nitrites? (five and one test strips)
  • And what about nitrates? (five and one test strips)
  • Have you tested pH? (five and one test strips)
  • Do you suspect low oxygen? (don’t assume a waterfall or small fountain will be enough in deeper ponds in the hot summer months)
  • Have you checked fish loading?  (overstocked ponds often have water quality or health problems)
  • Is your flow rate through the pond filtration system adequate? (ideally the full gallon volume will circulate about one time per hour or so)
  • Check your water temperature. (consider that warmer fish are normally healthier and less stressed plus fish medications are often not as effective in colder temperatures)
  • Inspect for any dangerous places in the pond. (are there any sharp edges on rocks, mechanical devices, etc that may injure a fish?)
  • How clean is the pond? (a natural pond doesn’t have to be pristine but it should be maintained in a relatively clean condition)

Common Fish Disease Causations

  • Consider bacterial infections.  (it’s important to get an anitbiotic into the fish but only after water quality and other root causations have been addressed)
  • Also consider fungal infections. (these are common in koi that are stress or debilitated)
  • Attack parasitic infections if they are suspected.
  • Consider viral infections.  (KHV – koi herpes virus is the most lethal and problematic because it can be spread so quickly and affect many fish in a pond)

Preparation Tips

  • Be sure to keep pond salt and some simple/common treatments on hand should you need them.
  • Have quarantine capability.
  • Use professional resources as needed for diagnosis, evaluation, and treatments if possible.
  • Consider bacterial infections.  (it’s important to get an anitbiotic into the fish but only after water quality and other root causations have been addressed)
  • Also consider fungal infections. (these are common in koi that are stress or debilitated)
  • Attack parasitic infections if they are suspected.
  • Consider viral infections.  (KHV – koi herpes virus is the most lethal and problematic because it can be spread so quickly and affect many fish in a pond)
  • Be sure to keep pond salt and some simple/common treatments on hand should you need them.
  • Have quarantine capability.
  • Use professional resources as needed for diagnosis, evaluation, and treatments if possible.

As you can see this is a fairly long checklist so let’s expand on a few of these topics and bring a bit more clarification to why these are important things to check and why they affect fish stress so much.

Fish Handling, Transportation, Seasonal Changes, And Feeding

Fish, like most wildlife, don’t like to be handled all that much.  Capture and extraction from the water is, in itself, a traumatic event, as is transportation to a new pond.  Touching an holding a fish should be minimal because it can disturb the natural and protective slime coating on their skin which once reduced can make infections easier to take root.

Fish generally prefer warmer water and their immune systems tend to work better in water temperatures in the mid 70’s.  As water temps drop and things cool off, fish tend to become more sluggish and their entire system slows down.  In good health they can  handle these kind of changes and do just fine, however if the immune system is compromised they may not handle things as well.  Winterstress is a time of particular concern when the weather is moving from cold to warmer spring weather.  As things warm up again, immunity will eventually improve once again.

Many people wonder how much they should be feeding their fish and it’s a good question to ask.  As a rule of thumb it’s good to feed fish about as much as they can consume in five minutes time.  Feed them slowly so that the food does not sink and go to waste.  By maintaining reasonable feeding amounts and scheduling you’ll have the best chance of avoiding water quality problems and maintain healthy fish.

It’s generally hard to overfeed fish and when they aren’t showing any further interested in eating or when the weather cools off below 50 degrees water temperature, then the feeding routine should be slowed or discontinued.  Thin fish can often be identified because they will have a very slender body and large head in proportion to the body.  Koi that are slow to grow, may be underfed as well.

Testing Your Pond Water

Every pond owner should get familiar with testing the water in their pond on a routine basis.  Really only two testing tools are needed for the most part.  Ammonia test strips test for ammonia of course, and 5 and 1 test strips will check for nitrites, nitrates, ph, alkalinity, water hardness.  These are all useful to know but most important are the ammonia and nitrite readings.  Both of these elements can be toxic to fish and cause widespread problems in a pond.  They are easily kept in check with beneficial bacteria supplementation and should you find any readings, some partial water changes over a period of several days will usually help to bring readings back into line.

pH readings are useful to know since this reading can affect not only fish health and stress.  Ammonia can become more toxic in higher pH ranges and in low pH ponds, there may not be much buffering capacity which can create wide swings throughout the day.  Fish would prefer a fairly stable pH reading at or above 7.0 and they can often easily tolerate readings up to 9.0 and a bit beyond it.  Some pond treatments and medications may also be affected by pH readings so it’s a good idea to get a reading on it before doing anything.

Low Oxygen And Your Fish

In warmer weather, pond water will not hold dissolved oxygen molecules as well as it can during cooler weather.  So when the heat of summer raises the water temperature above 78 degrees, it’s time to keep an eye on the fish to ensure they are not gasping for air, or appearing to be distressed.  Many people assume that a waterfall or small fountain will help with oxygen levels and while this is true to a point, if a pond has much depth, it may not help much in the deeper parts of the pond.  A small pond aerator may help protect the fish enough to avoid any problems even during hot weather.

An important point to note here as well is that during the summer, algae often can grow well in a small fish pond.  People may want to treat this problem directly but in doing so, if they kill the algae off quickly with a chemical, oxygen can be pulled from the water as the plant dies off.  It’s therefore important to maintain very good oxygenation during these times to keep your fish safe.

Fish Loading, Pond Filtration, and Pond Cleaning

Too many fish in a pond for it’s size will inevitably cause problems.  It always needs to be remembered that small ponds are enclosed systems with a limited amount of water volume and limits on a pond filtration system’s ability to deal with various things in the water.  There are several ratios that are mentioned from pond experts in terms of the amount of fish per gallons of water but a very good conservative number would be one inch of fish per ten gallons of pond water.  Less is even better, and more can lead to a number of problems with water quality.  Fish waste can build up and not be adequately handled which may lead to ammonia spikes, or algae problems due to the high nutrients in the water.

Many people might treat an algae bloom, and this includes green water and string algae, with an algaecide, however this does nothing to address the root cause of it all, which is excess fish waste due to high fish loads.  Good pond filtration will help with this of course, and one potential step would be to upgrade or increase the size and capacity of your pond filter.  However at some point, you’ll likely reach a threshold where a pond reaches it’s limits and problems can ensue from there.

Speaking of good pond filtration, it’s obviously important that the system be of adequate size and capacity to filter out the gallon volume of the pond, as well as handle an estimated number and size of fish in a pond.  It does little good to install a pond filter that’s undersized because they simply won’t help that much.  Also it’s critical that the flow or circulation rate of the water be moved in enough volume to allow the entire gallon amount of the pond to pass through the pond filter about once per hour or so.   This will insure that the water is being filtered well enough to remain clean, balanced, and healthy.

Normally a cleaner pond is a healthier pond so routine maintenance is a good practice to maintain fish health.  Pond vacuums are very popular today and in widespread use and they do help keep sediments, debris, and all kinds of things from building up.  Their prices vary widely so it’s worth shopping around to find the best setup for your pond.

Bacterial, Parasitic, and Viral Infections

As bad as the word “infection” might sound, many of these issues can be dealt with fairly easily with the right kind of treatment.  It’s important to use as targeted solution as possible but fortunately many conditions can be treated by salt baths, warmth, oral antibiotics, or other medications.

One of the very best diagnosing tools that you’ll find online is at KoiCrisis.com .  You can diagnose many issues by behavior or visible signs and there are lab diagnostics available as well.  This is about as thorough a resource as you’ll find and it’s run by an experienced veterinarian that can provide sound advice for anyone with a fish in crisis.

Many fish disease is an isolated case with only a single fish being affected.  However it’s also not uncommon to see certain ailments cause widespread harm to an entire fish population in a pond.  It’s due to cases like this when it’s useful to have the capability to quarantine a sick fish at the earliest signs of trouble.  This doesn’t have to be an elaborate set up but you need a way to provide a controlled tank that can hold the fish for a while in comfort.  Water temperature can be more easily managed, and medications can be more easily administered to a single fish in a confined space.  Prudent use of a fish quarantine station may end up being the best tool to keep the vast majority of your koi or gold fish safe.

This article is quite lengthy but it’s hard to provide a summary of everything that needs to be considered when you have a fish that’s showing signs of distress.  There is a lot that you’ll want to consider and evaluate when you try to pinpoint where the source of a problem may lie.  Doing so however is the best approach to take to end the problem quickly and restore your fish to excellent health.  We hope this information will help you do that in some way should you ever run into a problem.

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2 Responses to How To Effectively Deal With Pond Fish Problems

  1. Anna November 9, 2014 at 2:30 pm #

    I have frogs in my small pond and every spring I'm removing the dead frogs from the bottom of my pond. Should I just round up any frog and move them to a near by river now before it gets too cold or just hope they go back to where ever they came from.

    • pondtalk November 25, 2015 at 5:01 am #

      Hi Anna,

      I would just let them be, and they'll probably do just fine. Any dead one's certainly, I would remove them if you can.