Despite our very best efforts, fish health alerts and emergencies can occur completely by surprise. Problems can arise through no apparent fault of our own or can equally be as a direct result of our action. Either way, if we do not act swiftly and decisively during a possible problem, then what may have manifested itself as a minor concern perhaps affecting a single fish may eventually multiply to become a problem that may threaten the health of a balanced pond environment.
The first indication that all is not well with the fish life in a pond will be a change in fish behaviour.
What’s a change?
Of course, a change is only noticeable if you are confident of identifying ‘normal’ fish behaviour. You can only get a good feel for your fish’s behaviour by watching them regularly and getting accustomed to typical behaviour. Watching out for how long they usually take to come up to feed, how they usually respond to your shadow and whether certain fish in the pond are always more reluctant to feed than others are all important. It is these idiosyncrasies that make both your pond unique and you the best person to assess fish health – almost at a glance.
Changes in behaviour to look out for.
Fish Sulking. Sitting on the pond bottom or hanging just under the water’s surface. Fish are sluggish in their escape response when approached at close hand.
Loss of appetite. Fish do not respond at feeding time. Feeding fish with floating pellets is an ideal way of assessing the health of all of your fish. You should make a mental note of their number at feeding time and to see if any are abnormally reluctant to come to the surface.
Fish have fins clamped close to the body with dorsal fin not visibly erect. The fins on a healthy fish should be well splayed, tight and erect. Erect fins can be compared to a glossy coat of a cat in that they both indicate state of good health.
How and when to step in.
The 3 changes in behaviour discussed above can happen to either single fish or the whole pond. The course of action differs for either case.
All Fish Affected.
If all fish are less inclined to feed or are seen hanging and gasping at the surface then it is quite likely that there is a straight forward cause of the problem. The first place to check is the water quality.
A couple of test kits are essential to keep a check on water quality. These are pH and nitrite.
pH tests indicate whether the water is within the safe band of 7-8.5 with anything outside these levels (particularly less than 7) likely to cause stress and a change in behaviour.
Nitrite. This tests whether the pond biofilter is managing to breakdown the toxic fish waste quicker than it is being produced. The nitrite reading should be zero and any positive reading is a likely indication that this is the cause of the problems.
Possible causes of a nitrite reading are that there are too many fish for the pond, the fish are being overfed or the filter has not had chance to fully mature. Either way, the cause of action is to stop feeding, carry out a partial water change with fresh water and only start feeding if a zero nitrite reading is achieved. This should lead to an improvement in fish behaviour.
Other possible causes of stress in fish that may not be detected by pH and nitrite test kits yet cause all the fish to behave abnormally include:
a. Low dissolved oxygen. If dissolved oxygen is limiting, then fish can become sluggish and even seen gasping at the surface. This is easily remedied by the addition of extra aeration or increasing the water turnover.
b. Intoxication. Toxic chemicals and substances can accidentally be added to a pond which can cause fish great discomfort. Care should be taken when using insecticides or weed-killers near a pond as they can easily find their way into a pond, causing unpredictable problems.
Run-off from untreated lime in brickwork or patios can cause pH to soar above the safe limits of 8.5, again causing the fish to suffer.
c. Disease. The fish may have succumbed to a disease such as whitespot, gill flukes or other parasites. Depending upon the symptoms, these can be treated effectively with the correct medications. However, be careful to identify the disease accurately and dose correctly as overdosing will cause fish additional unnecessary stress.
Single fish Affected.
If only a single or a couple of fish in a pond appear to be affected, then this points to an isolated incident just affecting those fish such as localised damage caused by a bash or abrasion. It may be a weak fish succumbing to an isolated ailment such as an internal problem or genetic disorder. A single affected fish may also indicate the start of a larger problem, where so far, only this fish is affected. Single fish must be netted and inspected for any obvious damage or causative symptoms. If it is clear that the fish is unhealthy or damaged then the fish may have to be isolated and treated separately. However, there are cases where there is no external evidence of a cause for a change in behaviour. Treatment in such an instance may be counterproductive and it may be wise to return the fish to the pond and monitor it’s progress over the next few days. Check that it’s condition does not deteriorate or that other fish begin to show similar symptoms. If, after testing, the water quality is shown to be fine, then the provision of a healthy pond environment and food (if it has an appetite) may be enough to bring the fish back to full health.
In conclusion, ever since Adam and Eve sinned in the Garden of Eden, disease and health problems have been a way of life for us all, including fish. However, with a little time spent observing fish and managing the pond environment, it should be possible to curtail any health worries before they get out of control.