Can Anyone Confirm Diagnosis?

[iankent]

Hi everyone

It's not an emergency as such, as I think I've identified the problem, but just looking for a bit of confirmation on it! I bought 21 guppies from my LFS yesterday, added them to a new tank that's fully cycled (fishless cycling using media from main (healthy) community tank).

Almost all of the guppy have fin rot, which in itself isn't a major problem and can be treated. Most of them also have chunks taken out of their fins and tails! On about half of them the fin rot is so severe its down to the base of the fin, and in some cases there's no fin at all. They're kept in a tank with a betta at the LFS so I'm putting it down to that - I know guppy sometimes nip at each other, but I'm guessing a betta is the more likely culprit? I wish I'd paid a bit more attention when buying them!

In the last 24 hours they've been dying one by one - so far 11 have died and another isn't going to be far behind. I've checked the water levels every couple of hours and the results are a consistent Ammonia 0, Nitrite 0, Nitrate 10ppm, pH 7.2, temp 26C. As the fin rot is so advanced I can only assume the fin rot was present at LFS (past experience with fin rot tells me it isn't going to go from nothing to fatal in 24 hours!). The other tanks I have (one cory community, one mixed community and a betta tank) are all healthy, and I've not done anything differently when setting this one up.

By the time I got to death 6 I'd noticed a pattern starting to form. All of the fish that have died haven't been able to move one of their fins (not sure what they're called, the ones on the side near the gills) - it looks like the base has 'welded' in place due to fin rot and sort of pokes out the side of the fish unable to move, and after a while they give up trying to swim and a few minutes later they're upside down at the bottom dead.

Of the remaining fish, one has serious fin damage and I don't like his chances but the others appear to be mostly ok - still suffering from fin rot, but nowhere near as advanced.

Would you agree that firstly the fin rot would have been present at the LFS (i'm going to take a closer look at their guppy tanks tomorrow), and do you think its likely that the welded fins are the cause of death (either directly or through indirectly being unable to swim/stress of move/etc.)?

If my theory is right then I'm confident the remaining fish will go on to live happy lives! If not, does anyone have any suggestions on what else could be causing the sudden deaths?

Thanks in advance all

e2a: by the time I got to the end of this another fish has died - only one remaining fish seems to have any fin damage, but he does have some movement so I'm hopeful he'll recover. the rest now appear to have working fins (albeit damaged)

 

[LauraFrog]

There is a bacterial illness that causes finrot. It usually occurs on stressed fish (ie fish that have been recently moved, after being in a tank with a nippy betta, are prime candidates) and especially where the fins are already damaged - the betta, no doubt. It shows as white lines on the fins that gradually progress towards the body, usually appearing first on the tail and then spreading to the pectoral (behind gill plate) fins, resulting in the fish being unable to move them like you describe. It often appears in combination with a weaker strain of columnaris, so the fish that is already affected with finrot has a mouth turning white and often fuzz around the gills as well. It's often a deadly combination. I have cured it with antibiotics (tetracycline) and also seawater dips.

Even if you don't have this strain, most finrot is bacterial and some is fungal. Salt has an effect on both. As far as I can tell from your post the guppies are the only occupants of the tank. If this is the case, I'd suggest adding a hefty dose of salt, about 1.5-2 teaspoons/gallon. You can probably add more if you like. All livebearers can tolerate this much salt easily, I've got some guppies in brackish water twice this strength as their permanent home and they are fine. My LFS had finrot/columnaris combo to a whole batch of new guppies and halted the spread of the disease with salt, losing only the fish that were already seriously affected, some of the ones that had only started getting sick recovered.

In some forms of this disease the fish's death is actually caused by the bacterial infection itself and damage to the internal organs, and it occasionally shows dropsy before the fish dies, but it's possible that not being able to swim is accelerating their deaths by causing more stress.

Some photos would probably be helpful, we might be able to work out what sort of finrot it is. There are different sorts of bacteria that cause it and some finrot is fungal, so if we can identify the type of finrot it's a lot easier to choose a treatment that will kill it.

 

[iankent]

Hi LauraFrog - thanks for the reply, what you describe (lines appearing on fins etc.) is spot on. None of them appear to have mouth fungus at the moment though.

As an update, 14 of the 22 have died - the last of which died approx 36 hours after arriving in the new tank, and none have died in the past 12 hours, and only a total of 3 deaths in the past 24 hours. The remaining 8 guppies dont appear to have any serious problems with the fins, and all seem very active at the moment.

They are the only fish in the tank, and I've been slowly adding aquarium salt and 'Anti Fungus and Fin-Rot' (Interpet No 8). The aquarium salt is currently at about 1tsp per gal but will raise the level a bit higher throughout this evening. Didn't want to add it all in one go just in case that caused any additional stress!

Unfortunately it's a bit late to get any photos of the fish that have died, and none of the remaining ones are showing the same signs (they just have the usual white tipped fins and frayed edges, which the interpet no 8 seems to have cleared up a little bit since last night).

I'll be paying my LFS a visit soon and will try to gently persuade them not to keep betta and guppy together in future! I'll see if I can get any photos of the fin rot on the remaining fish to show you.

Thanks for the help you've put my mind at rest a bit - even though the fin rot damage was very advanced, there's always that little thing in the back of my mind wondering if its my fault!

e2a: there does appear to be one more with a dodgy fin, here's a photo - you can see the damage to the tail, and the top fin is also rotting, but the side fin I've got the photo of is fused in place and cant move - the fin on the other side moves fine: