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Quarantine is a diverse topic and one which cannot adequately be covered in a single post. It is a dynamic concept but one which is extremely valuable and which should be considered as a priority when purchasing ANY fishes for your home aquarium.
One of the most common problems associated with the introduction of new fishes is the introduction of their parasites which they may be carrying into your system. Of all the many problems, parasites pose one of the most important because many of them have the ability to reproduce quickly in a closed system using a single host to close their life-cycle. These parasites (those with a direct life-cycle) have the ability to be the most destructive. To begin with however, we need to try and understand what happens when a seemingly healthy fish is introduced into your home tank and shortly thereafter you have an infestation.
Parasites are incredibly well adapted organisms and demand much respect. Most are highly specialised and have evolved to fill a very specific niche so narrow that some are only found in a single micro-habitat in or on a host, on a single host species, without which they would cease to exist. Parasites and their hosts are constantly in a battle to survive. Parasites are evolving ways of evading the host immune system, while host fishes are evolving ways to exclude their parasites. This constant conflict, often referred to as the “parasitic arms race” reflects what is known as the Red Queen Hypothesis which states that in order to survive, these organisms are constantly having to “run on the spot to keep up.” So, there is an intricate balance then between the host, the parasite and the environment which may or may not lead to the outbreak of disease. This balance is called the host-parasite dynamic. If we look at each of these as factors, we can take a deeper look and get a deeper understanding of how each influences this dynamic.
Factor 1: Host (A fish population being invaded by a parasite has 3 mutually-exclusive cohorts that can change in relation to one another during the course of disease.)
Bear in mind that unless all of your fishes have been introduced this way, you may have a resident population of a parasite living comfortably within the realms of the dynamic equilibrium in your tank until this equilibrium is disturbed with the introduction of a new individual. It is common for a Cryptocaryon irritans infection for example to be present without exhibiting any symptoms of disease, but will be ticking over while being “managed” by the immune system of the various host fishes. The introduction of the new fish presents a susceptible individual which allows for a shift in the equilibrium and therefore the likelihood of the onset of disease. This often begins with the new individual but could then again spread to the others until the equilibrium is again satisfied.
So, given that I am rambling on a bit here, DO quarantine your new fishes. It reduces but does not exclude risk. How to quarantine? This is another long and complicated affair and deals with diagnosis, specific treatments that are tolerant of specific host species and an understanding of IPM (integrated parasite management). One also needs to consider the risks and assign priorities to certain conditions, but here are some basic pointers:
I hope that the above gives a basic introduction to quarantine but I find that an understanding of the question “why?” is often the most valuable – so keep asking this question until your queries are satisfied. Let’s together take quarantine and its many facets to the endth degree.
Regards
David
One of the most common problems associated with the introduction of new fishes is the introduction of their parasites which they may be carrying into your system. Of all the many problems, parasites pose one of the most important because many of them have the ability to reproduce quickly in a closed system using a single host to close their life-cycle. These parasites (those with a direct life-cycle) have the ability to be the most destructive. To begin with however, we need to try and understand what happens when a seemingly healthy fish is introduced into your home tank and shortly thereafter you have an infestation.
Parasites are incredibly well adapted organisms and demand much respect. Most are highly specialised and have evolved to fill a very specific niche so narrow that some are only found in a single micro-habitat in or on a host, on a single host species, without which they would cease to exist. Parasites and their hosts are constantly in a battle to survive. Parasites are evolving ways of evading the host immune system, while host fishes are evolving ways to exclude their parasites. This constant conflict, often referred to as the “parasitic arms race” reflects what is known as the Red Queen Hypothesis which states that in order to survive, these organisms are constantly having to “run on the spot to keep up.” So, there is an intricate balance then between the host, the parasite and the environment which may or may not lead to the outbreak of disease. This balance is called the host-parasite dynamic. If we look at each of these as factors, we can take a deeper look and get a deeper understanding of how each influences this dynamic.
Factor 1: Host (A fish population being invaded by a parasite has 3 mutually-exclusive cohorts that can change in relation to one another during the course of disease.)
- The susceptible group: those than can become infected
- The infected group: those susceptible, now infected
- The removed or immune group: acquired immunity or death
- The ability to infect a particular host species
- The parasite’s level of infectiveness (its pathogenicity)
- The parasite’s virulence
- The mode of parasitism
- Parasite or parasitoid?
- The environment can have a significant influence of the transmission and the development of disease
- Population density is critically important in the dissemination of disease
- Frequency of contact between the infected and susceptible hosts individuals (direct and indirect contact)
- Reduced host spatial arrangements and improved likelihood of successful invasion by re-infective stages
- Temperature, water quality, chemicals, water flow
- Stress and immunosuppression
Bear in mind that unless all of your fishes have been introduced this way, you may have a resident population of a parasite living comfortably within the realms of the dynamic equilibrium in your tank until this equilibrium is disturbed with the introduction of a new individual. It is common for a Cryptocaryon irritans infection for example to be present without exhibiting any symptoms of disease, but will be ticking over while being “managed” by the immune system of the various host fishes. The introduction of the new fish presents a susceptible individual which allows for a shift in the equilibrium and therefore the likelihood of the onset of disease. This often begins with the new individual but could then again spread to the others until the equilibrium is again satisfied.
So, given that I am rambling on a bit here, DO quarantine your new fishes. It reduces but does not exclude risk. How to quarantine? This is another long and complicated affair and deals with diagnosis, specific treatments that are tolerant of specific host species and an understanding of IPM (integrated parasite management). One also needs to consider the risks and assign priorities to certain conditions, but here are some basic pointers:
- Treat separate purchases of fishes separately and do not mix quarantine periods to add new fishes or break treatments
- Treat ubiquitous parasites (those of low host-specificity) with priority
- Ensure that your quarantine system is completely separate from your main system and use a separate set of nets and cleaning equipment for each
- Keep low levels of light in the quarantine tank with some structures for fishes to hide in
- Do not have substrate in your quarantine tank. This can harbour parasites and can also absorb some chemicals from treatments
- Ensure your climate control is tight (no wild fluctuations in temperature or general water quality). Use a filter that can maintain your water quality but one which can be used with treatments
- Feed good quality foods but keep to a minimum to avoid poor water quality
- Keep records of your quarantine periods, species quarantined, where they came from and any observations which you made that may be useful in future
I hope that the above gives a basic introduction to quarantine but I find that an understanding of the question “why?” is often the most valuable – so keep asking this question until your queries are satisfied. Let’s together take quarantine and its many facets to the endth degree.
Regards
David
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