Aquarium fish – pros and cons
The downside of a fish is that it is unlikely to form the same thread of understanding with its carer as a cat, dog or some rodent. And although it seems rather uninteractive, it is said to have many advantages. It is thought that watching fish in an aquarium can have a relaxing effect on the observer. Their colours and movements, on the other hand, can have a stimulating effect.
Fish are also rather low-maintenance pets. Like any pet, they require care, feeding and cleaning of their environment (here the aquarium). However, they do not require daily play or walks and can be left unattended, even for days. As long as you have properly prepared the aquarium in advance. Of course, taking proper care of fish requires a certain amount of knowledge, but the same can be said for any other animal. Can aquarium fish therefore be a safe alternative pet for an allergy sufferer?
Are there any known cases of allergy to aquarium fish?
Allergies to aquarium fish are not described, so it would seem that a fish would work well as a pet for an allergy sufferer. But is it really? Well, not really. Why? Because the fish lives in a humid environment that encourages mold growth, the aquarium has to be washed occasionally and the fish has to be fed.
So, we have three potentially allergenic risks. Of these, exposure to mold spores and ingredients in the fish’s food is considered the most significant for the allergist. Exposure to moulds can have many sources. Let us therefore focus on fish food as specifically related to fish.
Why can fish food be a risk for an allergy sufferer?
Aquarium fish food is a very broad topic. It is divided into artificial and natural. However, the basic ingredients of natural food are small water-dwelling organisms, i.e. slipper, rotifers, nymphs, daphnia, spa gudgeons, brine shrimp, pipefish and larvae of various insects (chironomid, water louse, mosquito). Such food may also be a live, frozen or dried form of food.
Many cases of allergic reactions to aquarium fish food have been described, manifesting as:
- rash,
- watery eyes,
- sneezing,
- runny nose,
- shortness of breath.
These reactions occurred both in people professionally involved in aquaria or fish food production and in people keeping fish at home. In the majority of the patients described, the cause of sensitisation was mainly to chironomids (Chironomidae) and daphnia (Daphnia). It was also noted that sensitisation to fish food was more common in people who were already sensitised to other allergens than in previously non-sensitised people.
It is estimated that the prevalence of sensitisation to daphnia in allergic asthma patients is more than 7%. It was noted that among patients who developed an allergic reaction to aquarium fish food, inhalant allergy to house dust mites was predominant, as well as food allergy to shrimps, crustaceans and other seafood. In addition, these individuals were also prone to a severe skin reaction to mosquito bites. In no study did the authors indicate previous sensitisation to furry animal allergens.
Which allergens are therefore present in aquarium fish food?
Pet fish food contains proteins from a variety of arthropod species, of which mainly the haemoglobins of chironomids (Chironomus) have so far been well studied for their antigenic role. Six different variants/variants of chironomus haemoglobin (Chironomus kiiensis and Chironomus thummi thummi) have been described and classified. All are considered allergenic after exposure by the airborne route (i.e. inhalant allergens).
Is only inhaling fish food risky?
However, it is worth noting that, in addition to haemoglobins, several tropomyosins (including those of chironomids, krill, gudgeons and small shrimps) have also been described among the allergens that aquarium fish food can be a source of. Other muscle-derived allergens, such as gudgeon myosin and arginine kinase, should also be added to these. All of these allergens can sensitise after both inhalation and oral exposure (should one accidentally ingest fish food). It is also impossible to ignore here that tropomyosins are a group of cross-reactive proteins that are recognised allergens of seafood, fish, mites and parasites. Furthermore, sensitisation to tropomyosins can cause severe allergic reactions following exposure to this allergen of those allergic to it.
How do allergies to aquarium fish food allergens occur?
It has been noted that symptoms of allergy to aquarium fish food can occur in people who have previously had contact with fish food, as well as in people who have never been exposed to such exposure. This allows us to assume that these patients could have become allergic to these allergens in various ways. The first thing to consider is inhaling particles of “insect” components of fish food or cross-reaction with other allergens. These include mites, shrimp or mosquitoes.
Aquarium fish – are they safe for allergy sufferers?
Yes and no. If you like fish, they can be a safe alternative to a pet. However, you should remember that fish food can cause allergic reactions, especially in people who are allergic to house dust and seafood, and those who do not tolerate mosquito bites well. In such a situation, it is better to ask someone else to feed the fish.
