Switch language Language

Interview with Dr Gerd Großheider on tropical fish diseases

Dr Gerd Großheider, Director of Quality Management and Regulatory Affairs at Tetra Dr Gerd Großheider, what are the most common tropical fish diseases and how can they be recognised?

Dr Gerd Großheider, Director of Quality Management and Regulatory Affairs at Tetra:
The most commonly observed symptoms of disease in freshwater tropical fish include inflammation and infection of the skin, ulcers, white spots or coatings, as well as dull mucous membranes, frayed fins, noticeably laboured breathing or white, cotton wool-like areas on the fish skin. Peculiar behaviour, such as staying in the corner of the aquarium, exceptional timidity or fish that exhibit darting and jerking movements, as well as distinctly rapid breathing, are also signs of disease.

What causes these diseases, or rather how do pathogens enter the aquarium?

GG: There is generally a distinction made between so-called multifactorial diseases and pathogenic diseases. The symptoms listed above are predominantly caused by pathogenic diseases. By contrast, multifactorial diseases can be attributed to several contributing factors such as malnutrition, social stress, poor or inappropriate water chemistry and even problems relating to equipment, e.g. in terms of temperature and aeration, which drastically reduce fish resilience and thus create the perfect environment for so-called opportunistic pathogens.

Fungal or bacterial infections are common during the course of such diseases, in addition to abdominal dropsy or reddening of fish skin due to minor haemorrhaging. In most warm water aquariums, the water already contains the relevant germs, but the immune system of healthy fish succeeds in keeping these at bay, provided that the pathogen pressure does not become too great. Any aquarist presented with this situation must look into the conditions of their tank.
There are also highly aggressive and contagious pathogens, which are feared for good reason. Often, these include parasites that attack even healthy fish. For example, every experienced aquarist should be familiar with the term Ichthyophthirius multifiliis, a protozoa that deserves its status as one of the most dreaded fish parasites. As well as carrying out instant treatment, sufficient hygiene measures are also of great importance here to prevent the disease from spreading to other tanks.

From your experience, are veterinarians well versed in tropical fish diseases, or is it sometimes better to ask an experienced, specialist aquarium dealer for advice?

GG: As a general rule, fish disease does not play an important role as a compulsory part of veterinary training and only a handful of vets have a genuine interest in the field. In contrast to other parts of the training, students are not exposed to the specific characteristics of fishkeeping which, needless to say, is a prerequisite for carrying out successful treatment. The task of a veterinarian, who holds no interest in aquatics, is not made any easier by the fact that fishkeeping involves several hundred different species of animal. It can generally be assumed that some veterinarians, either through greater access to fish or through a certain amount of passion for fish that they have developed in their own hobbies, are also able to provide effective care in many cases. However, they represent only a very small group, and while this does include a number of highly-qualified veterinarians specialising in fish disease,  it is clear that they can in no way meet the demands of the entire population.

What is the situation regarding over-the-counter remedies?

Tetra Medica LifeguardGG: At the last Interzoo trade fair, we launched the over-the-counter remedy Tetra Medica Lifeguard that fights the most common ailments of tropical fish. It can be used to treat the first signs of disease thanks to its non-antibiotic, broad-spectrum active ingredient. One water-soluble tablet of this over-the-counter remedy contains a 75 mg dose of 1-chloro-2,2,5,5-tetramethyl-4-imidazolidinone as an active pharmaceutical ingredient. The remedy’s strong oxidising properties destroy the various pathogens, whilst its active chlorine content disinfects the aquarium water. This prevents further spread of the pathogens. We developed Tetra Medica Lifeguard in collaboration with the Center for Fish and Wildlife Medicine at the University of Bern in Switzerland. The intensive research carried out there showed that the remedy is at its most effective during the many different stages of ichthyophthirius multifiliis, otherwise known as “white spot disease”. Only around four hours after the first tablet is used, the pathogen concentration of free swimmers (theronts) decreases considerably, thus preventing the spread of the disease much faster than was possible with conventional products.

What should be taken into consideration when using this product?

GG: Our fundamental goal is to make our products as safe and user-friendly as possible. Even the dosing process for Tetra Medica Lifeguard conforms to this approach. First of all, 20 per cent of the water should be changed without adding any water conditioner. Then, one tablet per 30 litres of aquarium water should be added to the tank every 24 hours for five consecutive days. During treatment, it is important to keep the aquarium well aerated, to avoid using absorbent filter media, such as activated carbon or synthetic resin, and to switch off any UV clarifiers, ozone systems and CO2 fertilisation equipment. There are no known side effects or contraindications associated with Tetra Medica Lifeguard and the product is recommended for use in disease prevention.
Tetra Newsletter