Many of the more exotic display units, particularly the 'toy' aquaria and those incorporated into light fittings are designed principally for their visual appeal or novelty and pay scant regard to the welfare of the contained fish.
A major problem when trying to ensure the health and welfare of fish is that many species, although by no means all are extremely cheap and easily replaced and the occasional loss through lack of care or inappropriate conditions may be seen as acceptable. Just as much consideration should be given to providing the best possible conditions for the health and welfare of a tank of guppies worth a few pounds as for a koi worth many thousands of pounds.
A great deal of attention should therefore be given to providing the best conditions for your fish. They are being confined in an environment from which there is no escape if something is wrong and it is the owner's responsibility to ensure that the environment is suitable at all times.
Providing the correct conditions can sometimes be difficult. Environmental demands can vary markedly between different species and the requirements for one species may be totally different from those of another. A classic example of this is Rift Valley cichlids which demand an alkaline pH compared with the acidic conditions demanded by many tropical fish originating from jungle streams. It has been estimated that a third of aquarium fish are being held in water which is unsuitable for that particular species and anyone intending to keep pet fish should really investigate the water quality characteristics of the environment they are providing. This will allow them to direct their purchases towards species which are comfortable in that environment. The 'community tank', where several different species are kept together poses particular problems with compatibility between species in terms of environmental requirements, feeding behaviour and aggression. Aggressive behaviour between fish will cause stress, injury and predisposition to disease. A reputable dealer will be able to help in determining the best species for your system and compatibility between species.
The size and siting of any aquarium or pond are very important. In general the larger the volume of water the unit holds the more stable and easier to maintain it will be in terms of water quality and environmental conditions. For example a small, shallow pond will heat up very rapidly on a warm summer's day compared to a larger deeper pond. It is always better to go for the largest unit possible and the traditional goldfish bowl and other small units should be avoided.
Siting is critical in maintaining a stable environment. Aquaria should be sited away from direct sunlight and also away from sources of noise and vibration e.g. washing machines, which can have a significant impact on the welfare of the fish. Avoid any potential cause of poisoning and contamination e.g. domestic cleaning products and pest killers. Remember that nicotine is readily soluble and acutely toxic to fish and aquaria should not be sited in smoky atmospheres, particularly if air pumps draw smoke-laden air through the water. With ponds contamination from toxic plants and trees and garden chemicals must be avoided; shading and hiding places against bird and animal predators must also be provided.
It takes a long time to establish a stable pond or aquarium environment and, all too often, people are so keen to get their system up and running that they stock it with too many fish before the system can cope. The result is the 'new tank syndrome' with serious deterioration in water quality, a build up of waste products from the fish leading to severe fish health and welfare problems and, frequently, the death of all the stock.
Patience is essential in setting up a successful fish unit. Filters must be given time to mature to enable them to cope with the fish waste products and new set ups must have a very small number of fish to start with. Filters can be helped by feeding with bacterial cultures and nutrients, but it is still necessary to add new fish very gradually to ensure that the filter is able to cope with the additional waste materials (ammonia) produced by the fish. With marine aquaria the establishment of a stable environment will take even longer than a fresh water system and it may be a year before a really stable set up is achieved.
Overstocking and overfeeding are two commonly encountered problems. There is a limit to the number of fish which can safely be stocked in any unit without there being a detrimental impact on water quality and fish welfare and this limit is often lower than people would like for an attractive display. Allowance must be made for growth of the fish and also any invertebrates present (particularly in marine aquaria). The number of fish which an aquarium or pond will hold is commonly determined by the surface area of the water and the total length of fish held in the unit. As a general guide 2.5 cm of fish (excluding the tail) can be stocked for every 72 square cm of available surface area. For goldfish in aquaria the available surface area should be twice this figure. With pond fish a more common guideline is 2 kg fish per 1000 litres of water. These figures are based on a well established system with optimum water quality.
Most pet fish are overfed. There is always a tendency to give more feed than the fish actually require and the consequent waste feed can have a seriously detrimental effect on water quality. It is very important to judge the feeding behaviour of the fish, trying to feed to appetite, but to decrease if feed remains uneaten after a few minutes. The amount of feed a fish requires is governed by many factors including the species concerned, the age and activity, the water temperature. Good observation and knowledge of requirements is essential. Some species, particularly marines, have extremely demanding feed requirements and these are best avoided by novice (and even some experienced) hobbyists. There are a few specimens which are totally unsuitable for domestic aquaria and, again a reputable dealer should not stock or sell these. The Marine Aquarium Council is working towards a certification scheme which will promote high standards for the marine ornamental trade including environmentally responsible and sustainable collection of specimens from the wild. It is hoped that these standards will be widely adopted by the trade to promote good practice and to raise awareness of the need for high standards of fish health and welfare.
Fish purchased from a reputable dealer should be in good condition and generally healthy and it is important to buy fish which do appear to be healthy. Quarantine facilities are useful to allow observation for disease for a few weeks before the fish are introduced into an established set up but if this is not possible then close monitoring for signs of ill health such as poor appetite, lethargy, damage, irritation etc. is essential. The continuing health of the fish can only be assured if they are not stressed and their welfare compromised in any way. Poor water quality, lack of hygiene, incompatibility with other species, lack of appropriate diet and overcrowding all stress the fish and make them much more vulnerable to disease and death. There should be constant monitoring for signs of ill health and professional advice sought if there are signs that a problem is developing.
If proper attention is paid to the welfare of pet fish at all times, it is less likely that they will suffer stress and ill health and have better chance of surviving into old age. Old age brings its own set of problems and there may come a time when it is considered necessary to put an old, ailing fish to sleep. The welfare of the fish at this time must still be considered and professional advice sought if necessary. Please don't just flush it down the toilet!
Some golden rules
Only keep species of fish for which the correct conditions, care and feeding can be provided
Purchase fish from a reputable outlet registered with the Ornamental Aquatic Trade Association (OATA)
Avoid small containers
Take time to allow the aquarium or pond to establish and for the filter to mature
Gradually add fish to the system as it becomes established
Do not overstock
Do not overfeed
Monitor water quality
Observe for signs of ill health, poor condition, and aggressive behaviour
Seek advice and get a good book