Originally Posted by Kaddock
I need some help. I have three tanks, 10, 28, and 38 gallon (all well established, 1-3 years). They have all been doing very well for some time now. Out of the blue, fin rot pops onto my guppies in the 10g and my corys in the 28... Same time! No biggy, went for the triple sulfa (my idea), then Kanaplex... Then erythromycin, then pack to Kanaplex (following directions and water changes schedules and advice from fish store man). The guppies continue to have symptoms (it's been maybe a month of treating). Meanwhile, I've of course been doing weekly water changes. The water quality in all three tank remains flawless upon testing (only a minor ammonia spike once in the 38, cleared in a day). I'm pretty sure the corys never lost the rot either... And, now the largest cory has a giant swelling under his chin, making a kissy face almost. Prazipro was recommended, which I have administered twice in three weeks to no affect (none of my tanks have carbon in case you were wondering). Now, the 28 gallon is going berserk! Cory with missing whiskers and fins, a black phantom headstanding very slightly, a gold barb doing the irritated twitch and rock scrape, and an otocynclus with scarlet red belly and mouth to top it all off. I turn to my 38 and smile with satisfaction... But wait, what's that red abrasion on that gourami, and did tetra just do the rock scrape dance? I am struggling not to type the curses that are rolling through my brain! Sooooo frustrated. Please help before I end up spending hundreds of dollars on meds and losing all my fish anyway.
I have had this problem with almost all of my fish that have gotten sick in the past year, no meds cure them.
First ,I should say that I am no expert but were it me,, I would run some new,fresh carbon in the three tanks for a couple three days to remove residuals from all of the meds you have been using that water changes alone may not remove.
Would also get aggressive with gravel vaccuming on one half of the substrate in each tank ,and the other half the following week during water change.
Have any new fishes been added to the tanks recently?(pathogens possibly introduced)
Do note that guppies need basic alkaline water with pH between 7.5 and 8.0 and temps around 78 to 80 degrees F to do well in the long term and that male guppies ,especially fancy guppies,,, will nip the fins of other males in tanks where they are numerous ,or tanks where few females are present.(may not be fin rot)
Cory's spend a lot of time on the substrate so keeping it clean is important lest they damage their barbels and infection from bacteria present on and in the substrate lead to secondary infections. Sharp substrate or decor can also contribute to possible damage.
Some gourami's are prone to bacterial or viral infections such as the dwarf gourami and it is speculated that this can be transmitted to some other species,(see Iridovirus in dwarf gourami) Is unclear as to what may trigger this but is something you may wish to consider.
Tetra's and barbs often do poorly when kept as singleton's and prefer to be in groups =less stress and fish that are stressed,are mor suceptible to disease.
Water chemistry fluctuations or temp fluctuations are also contributers to problems and perhaps these areas should be explored as well. With all of the meds you have recently used,,the fishes are no doubt in less than stable conditions and thus my suggestion of running some carbon in your filters for a few days to remove any residual medications from the tanks.I might also perform 25 to 30 percent water changes twice a week for a couple weeks using a dechlorinator such as PRIME for new water before it goes in the tank.
Water treatment plants sometimes during the spring and fall increase the levels of chlorine or chloramines that they use and if you are using tapwater,this may mean that dechlorinator dose needs to be doubled and PRIME is safe to use at double the recommended dose
As stated,, I'm no expert but these are some things I would consider were it me (and it ain't).
Redness could be bacterial and in this case,, once I cleared the tanks of meds and cleaned substrate,, I might consider Maracyn ,Maracyn II treatment but would not do so unless condition worsened after I tried the above mentioned carbon,substrate cleaning,and twice weekly water changes. Opinions Vary.