I'm really hoping it doesn't affect pyjamas, since I do have four in the DT which could have been exposed to the pathogen via the peppermint shrimp I added to the display. I think they may have come up with a vaccine for iridovirus in red sea bream, but again, scientists generally consider iridoviruses in different species to be unique to said host.
Banggai #4 died sooner than expected, so we sent him to our local exotic vet to be shipped off to PEI for full testing. It'll probably be too late by the time we get results back (we honestly should've sent the first fish in when it died so we'd have a chance of preventing further deaths, should this mystery illness be treatable), but it should tell us what's going on with them. As a result of this whole ordeal with Banggai, from now on we'll be sending any fish who dies in quarantine or in our display to PEI for a full workup to nip any potential issues in the bud and prevent spreading any potential illnesses. I'm also going to start examining the feces of our DT fish on a regular basis to check parasitic load to ensure good health. Additionally, we're only going to be buying our critters from J&L Aquatics, as they receive the vast majority of their critters directly from breeders and collectors (rather than from wholesalers), quarantine all fish, make sure all fish are reliably eating, and only tend to sell captive-bred individuals from species that are available captive-bred (for example, they'll sell wild-caught Naso tangs since they aren't available captive-bred, but they'll only sell captive-bred Banggai, captive-bred watchman gobies, captive-bred orchid dottybacks, etc.). This greatly reduces the risk of fish being exposed to anything contagious. Oh, and we're going to be quarantining any new acquisitions for at LEAST two months, if not four months.
It's honestly frustrating trying to gather information on this pathogen. They go into great detail on iridovirus in food fish, but not in ornamentals.
From what I understand, in the 90s, Banggai cardinalfish were considered to be tough as nails and a great beginner fish. By the early 2000s, Banggai cardinalfish being held in shipping facilities, wholesalers, and retailers started dropping like flies. Whole shipments were being lost, while others were completely fine, and people were at a loss. These fish, even the wild-caught ones, are known for being very easy to feed, easy to catch from the ocean (they don't hide and aren't very fast, so they aren't harvested using cyanide), confident (compared to tangs and other wild-caught fish), and are perfectly happy living in nano tanks. The fish who died often looked completely healthy, save for gill movement and refusing food. For the most part, they didn't have any lumps or bumps, their fins were fine, eyes were clear, and their colouration was good (some individuals had slight hemorrhaging and/or discolouration in the front half of their body).
To quote Banggai Cardinalfish: A Guide to Captive Care, Breeding, & Natural History, "In 2009, several scientists, including Banggai Rescue International Science Team member Dr. Thomas Waltzek, published a groundbreaking paper in the Journal of Vetrinary Diagnostic Investigation linking the Banggai Cardinalfish deaths to an iridovirus."
It was in the 90s when breeding facilities in North America (for both food fish and ornamental species, such as gourami) first started having problems with iridovirus. Many researchers suggest that wild Banggai cardinalfish populations aren't carriers of the disease, but rather exposure to other fish species carrying the virus while in holding facilities has caused it's spread among Banggai.
Honestly, the biosecurity at these places are terrible. Hundreds of species, from all over the planet, are being housed in these facilities, often sharing the same water. It's like when Europeans came to North America. Millions of Natives died from smallpox because they had no immunity to the nasty pathogens white people carried over from Europe.
It's exactly the same as with the poor wild-caught parrots (birds). Back in the day before parrots were being bred in captivity, terrified, often injured birds from completely different counties were being kept in tiny cages in facilities filled with hundreds, if not thousands of birds. Avian bornavirus, PBFD, New Castle's Disease, air sac mites... dozens of deadly, highly contagious pathogens were spread like wildfire. Only an idiot (no offence) would buy a wild-caught parrot. They are wild animals through and through (captive-bred ones are extremely wild as well; I regularly adopt small parrot species from shelters, especially birds who have psychological problems), and no matter how "cool" you think they are, you have to remember that they require tons of mental stimulation, an expensive diet, plenty of room to fly, and must be treated as one's equal. Parrots, regardless of species (whether they're a budgie, a parrotlet, quaker, or macaw), tend to be very proud (just like humans), and don't take well to being treated like they're lesser than you. You have to be a gentle, patient parent to them, teaching them how to express their anger and frustration in healthy manner (never show fear or anger toward a parrot who wants to bite you, as this makes the behaviour worse), encouraging them to do as you ask by teaching them through rewards and never force (a lot of people teach parrots to step up by forcing them onto a hand held perch or their arm, whereas it's far more effective and easier to teach them to step up freely using target training), and respecting their right to privacy and personal space. I hate nothing more than when I see someone forcing themselves on a parrot who hasn't consented to being touched or picked up.
Sorry, got off topic there for a bit, but it's important information everyone should know should they ever meet a parrot some day. Actually, the advice above applies when interacting with any species.
Anyways, I've dealt with outbreaks of deadly illnesses in my own freshwater tanks and avian gastric yeast in my aviary. All my freshwater tanks are infected with Mycobacterium marinum (aka fish TB), and the saltwater tank likely has been exposed as well. To be fair, I'm pretty sure every captive aquatic critter has been exposed to TB, it's just that most people don't have necropsies performed. Like, this pathogen is found absolutely everywhere and is super contagious. The only way to prevent your tank from getting Mycobacterium is to never put any corals, invertebrates, plants, macroalgae, live rock, frozen food, etc. in your tank, as they all could've been exposed at some point to TB. And guess what? TB can reproduce without a host and survive indefinitely out of water. Any time you get new fish, you have to quarantine for several months, then euthanize one of them and have it analyzed in a lab for TB, since fish infected with the disease can, and often will, go their entire life without showing any signs of disease. So, what happens if your tank gets infected with TB? Well, you're supposed to euthanize everyone, throw out nearly everything in the tank, scrub it, then use industrial strength bleach on the tank for 30 minutes. But guess what? TB is extremely resistant to disinfectants and most antibiotics, so odds are you missed a tiny spec of biofilm in your tank which is harbouring the pathogen, and now it's just biding it's time until you think the tank is sterilized and safe to use again (then it will immediately infect any vertebrate you put in the tank).
If a single drop of water with Mycobacterium in it, or a dust particle comes in contact with any of your critters, equipment, live food, etc., you have now introduced TB to your tank. So, basically, you can have the most amazing biosecurity protocols in place, but at some point, through no fault of your own, your tank is definitely going to be exposed to the dreaded TB (ALL cold-blooded vertebrates can contract and die from TB). The only way to keep the TB under control is to make sure your fish don't experience stress and to make sure their microbiomes stay nice and diverse, never use antibiotics in your display (this will just kill off weaker species of bacteria, allowing the highly resistant TB to take over), and to make sure to maintain a wide variety of microbes in your tank (it's good to regularly add live sand from fellow hobbyists' disease-free tanks to prevent any one microbe from becoming too over-represented. A pathogen typically only causes harm if their aren't thousands of other species of bacteria, fungi, virus, parasites, etc., to keep their population in check).
In conclusion to my whole rant on TB, the advice to start over from scratch each and every time your tank contracts TB is stupid. As long as you follow my "low-stress and microbial diversity theory" and euthanize, or at least relocate to their own "leper tank", any fish displaying outward signs of illness, your fish should be able to live very happily for a very long time. Just be aware that if the amount of TB in your tank is high, any juvenile fish introduced to the tank are likely to have a far shorter lifespan as they are very fragile when it comes to TB (it's like how the elderly tend to die from the flu, whereas younger individuals don't).
. This is the very reason why the critters I buy for the reef tank all have long lifespans, are captive-bred, and/or I can breed them to maintain their numbers without having to buy more fish who could easily be harbouring deadly pathogens. That's one of the reasons I cringe whenever I see mollies recommended for saltwater tanks. Any fish that breeds that readily, is so inexpensive, can be kept in nearly any tank chemistry, is routinely used as a feeder animal, and is often kept in over-crowded tanks is bound to be carrying dozens of different pathogens. In fact, it's livebearers that tend to be most affected by TB in my tanks. They tend to be absolutely filled with granulomas from the pathogen.
