Right now, the world is seeing a threat sweep through in a manner largely unknown in our age and it seems timely to reflect on the parallels with our aquatic pets, especially as many of us will be spending a bit more time with them! Of course, I hope you are blessed with good health and plenty of toilet paper and that my ramblings serve to provide some distraction.
In the aquatic trade there’s a number of viral issues that we’ve grown accustomed to dealing with, these are mostly very specific and pose no threat to humans of course. Let’s start with a couple of the most well established ones...
Lymphocystis is the cauliflower growths seen in tropical fish, both freshwater and marine. It used to be commonly seen in the dye-injected Glass perch we discussed previously, as typically they would share dirty needles in a way seen only in soap opera drug addicts. You’ll still see it occasionally in batches of newly imported fishes and the cure is simply to reduce stress and boost the immune system to let things take care of themselves. It’s not usually life threatening but merely unsightly, so good water quality combined with stress reduction and a diet that fortifies the immune system are the keys to its cure.
Carp pox (Cyprinid Herpesvirus 1 or CyHV-1) is a herpes virus that gives affected fishes (usually koi) the appearance of waxy lumps, normally white in colour. Typically these appear when affected fishes are exposed to environmental changes such as temperature fluctuations, therefore they’re more commonly seen in the colder months, as this is very much a pond fish malady. Carp pox is another virus that’s largely benign and typically fish that are carriers will only show symptoms for a limited period each year before the warmth of spring gets their immune systems into gear.
Both these viruses are commonly seen and can be alarming but usually disappear with little intervention from us, aside from good husbandry.
There are others that are far more harmful and if you’re feeling the wrath of Covid-19, you may feel a bit better knowing you’re not as badly off as some other poor creatures.
I remember decades ago causing chaos in my community tank by adding a pair of Dwarf gouramis (Trichogaster lalius). The male ferociously claimed a corner of the aquarium and proceeded to tear at the plants to make a nest while he courted the chunky female. They were colourful, hardy and cheap enough that I could afford them on my pocket money. Over the last twenty years, these hardy staples have become a tricky fish to source, as many of them now suffer with Dwarf gourami iridovirus (DGIV) that is species-specific and incurable. This widespread disease hit the big breeders first, so cheaper producers had the worst fish and I vividly recall a conversation with a customer who told me emphatically that they’d rather buy the cheap but doomed fishes (!) when challenged to defend a difference in price. This species is fairly short-lived anyway but this may be linked to a distribution which lies in areas that experience cooler winters and sees them burn out when deprived of a slightly cooler seasonal rest. Certainly, the wild Indian imports I’ve worked with tend to come in small and silvery before coming into breeding condition - perhaps an area where some experimentation is needed. Either way, the lesson is to buy this species with care and perhaps consider alternatives such as the Honey gourami (Trichogaster chuna).
The other viruses also target a single species but this time a very significant one - Koi (Cyprinus carpio). These are the reason why we can no longer accept fishes from customers’ ponds as biosecurity is key to ensuring continued safety.
Koi herpesvirus or KHV (Cyprinid herpesvirus 3 or CyHV-3) is a notifiable disease like foot & mouth, with a mortality rate of up to 100%. Unlike the very innocent Carp pox, KHV becomes active at higher trigger temperatures and so infected fish are undetectable at cooler temperatures, with sudden mortalities occurring when temperatures climb into the high teens. All the carp coming into our stores are now screened for KHV and as with the gouramis, many sources are now unsafe to buy from, leading to the disappearance of the cheaper mass-produced koi that used to be the starting point for many pond keepers.
As if KHV wasn’t nightmarish enough, a second disease - SVC (Spring viraemia of carp) is a relative of rabies which is, as the name implies, a disease that becomes active in the cooler conditions of spring at temperatures of around 8c and above. Unlike KHV, SVC has been found to occur in a range of species and much work has been done to attempt to make the UK free of this disease.
So, there’s an insight into some of the viral issues we’ve been handling quietly in the background for years. Who knows what the future brings but certainly this group of pathogens have never been more high profile. They’re just one of many things that have a great deal to do with the price of fish, to paraphrase an old saying.
For now, I wish you good health and biosecurity until next time when I’ll probably be back on the warpath about something or other...
Old favourites tend to be in the hobby for a long time with good reason, usually, it’s because they combine a lot of desirable traits. The metallic form of the Gold barb (Barbodes semifasciolatus) makes an excellent aquarium fish suitable for both tropical and temperate (unheated) setups. These young fishes at our Pyle store are a perfect beginner’s choice.
It’s that time of year when the heating goes back on, and this is something that many of us have in common with our pets. To ensure they remain healthy, it’s important to know that your aquarium heater is working properly and is set to the right temperature for the fishes you keep.