But I doubt the majority of early wipeouts are from things test kits can pick up. I know, heresy. I've nosed around a few warehouses holding many hundreds of tanks - the suppliers who often receive fish from the tropical farms and then distribute those fish to shops. One employee said the business side of the cheaper fish (the ones the chains like) is a race - will they die before they're sold? They tank them and try to get them out the next day if they can. It's all about turnover.
I might be overstating it by saying that most threads turn out to be an uncycled tank/ammonia spikes etc, but it does happen pretty often, and most of us can talk someone through something like that. Then, as you say, we might find underlying disease too. Especially with the fish you mentioned!
When I started in the hobby about three years ago, I just wanted a little 15g guppy/shrimp tank. I always do my research before acquiring a pet, and I'd been maintaining my elderly father's tank for a while as well, so I threw myself into research while I did a seeded cycle on the 15g using media and substrate from my dad's tank. I watched dozens of youtube fish channels, read around places like here, read books, learned about the cycle, bought an API test kit, bought live plants and took cuttings from dad's, etc etc. Borrowed some of his baby mollies to try in the 15g eventually to help make sure it was cycled. Once it was testing perfectly, I went to the store and got a trio of guppies.
My folks were in the aquatic business for a long time, so I thought guppies were still the hardy beginner fish they always were known to be, I'm sure you remember when that was their reputation. But they've been out of the business for 30 odd years now, and didn't know how things have changed. I loved this trio of guppies, they were super pretty, looked healthy, then they died within 24 hours. Hadn't seen signs of illness, water was testing perfectly, 0/0/<10. Shop replaced them, the next ones died one by one over the next week or two. By my third attempt, while seeking advice on FB groups and not getting much help since my set up seemed fine, I finally was told that guppies are weak and unhealthy now, since being bred in giant fish farms, over medicated, raised in seawater, not quarantined, not well bred etc. I felt like a fish murderer though, and that perhaps I should give up. When the third group died, I decided to give it one more try, getting fish from a different store, and this time I got six females and two males. Of course, this time they all lived, and the six females began churning fry at a crazy rate! So I got more tanks...
But, after about six months, some where getting skinny and lethargic, and dying off. fry that were about 2 months old were dying. I was told worms were likely, used a generic wormer without results. Finally saw the red brush signs of camallanus, and learned about the right meds to treat them, and it was a pain to treat every tank!
So like many, I learned how important it is to quarantine new stock, and one thing I would medicate immediately is to worm any livebearers while in quarantine, with the right meds for round and flat worms. So yes, I agree with you, and I learned the hard way! I really almost gave up though, since I couldn't figure out what I was doing wrong to lose all these guppies. I've since heard that if you buy guppies, that if you can get some fry before the originals die, then you're doing well, and the fry should be hardier than the parents were.
♂
