This question isn't referring to a single sick fish per se, but more of a general question related to higher-than-normal rates of fish loss: at what point do I just completely break down the tank and start over?
I have a 20g high tank set up and cycled for ~18 mo now. I had to move the tank to my office for what I thought would be a short duration for a large home renovation, but that has now turned into a year, and it's proven to be a challenging place to maintain it, due to weekends, work trips, and the unavoidable placement in a spot that gets some direct sunlight (despite keeping the blinds closed as much as possible. but have to keep open periodically for all the houseplants I have). It is moderately planted with java moss, various java ferns, Anubias, and some bacopa. At any one time I have ~8-10 neon tetras and 4-6 cory cats (trilineatus), some ramshorn snails, and 2 assassin snails. It has a HOB
filter, and I do 25% PWE every 1-2 weeks, depending on my schedule. Parameters are always 0/0/~5-10 whenever I check, temp 76F.
Over the past year since moving my tank, I would say that I am losing fish at an average rate of ~1/month. Often, the fish will have no symptoms and just show up dead. There have been other times when I've had fish suffering from obvious bacterial infections, probably Columnaris, that I've never been able to successfully treat, either in the main display tank or quarantine tank.
I feel like that is just too high a rate of loss and I am strongly considered just taking everything apart, disinfecting everything, and starting over from scratch. probably when I can move the tank back home, hopefully in another 1-2 months. I understand that a lot of the same pathogens can repopulate the tank once I set it up anew, but maybe 18 months now of experience under my belt and a set-up in a more stable environment will be enough to keep the infections at more of a minimum.
Just curious what other folks would do/have done in this sort of situation.
Thanks in advance...