fin rot spreading through my tank?

[danielle's tank]

Today I was looking at my silver dollars and realized that their fins don't look so hot 2 of them have huge amounts that are disappearing. The other day I noticed that one of my angels had a hole through the fin, today that hole is a rip so now that is four fish in a matter of days with fin problems. Is this fin rot and what can I do about it? I know an RA at my university clipped her fishes fin when this happened to her fish (this is actually how I even know that fin rot exists) is this feesable or not really for someone inexperienced like myself. Is there a medication I can get and put in the water or will all my fish get this and die

[MatsP]

What is happening, most likely, is that your ammonia and/or nitrite is hurting your fish.

Do a large water change(50%), and they'll probably heal eventually.

There are medications, but I'd say your first priority is to get the water conditions good.

--
mats

[Birger]

I would also have a good look at the interaction between the Botia and the other fish, if the fins are looking ripped it is very possible to suspect some chasing and or nipping especially as the Botia learn they are in charge.

Birger

[Dave Rinaldo]

Yasuhikotakia modesta are one of the 'nastier' loach species.

Because of their size and temperament, Y. modesta should only be kept with other boisterous loach species, or large, fast moving, free-swimming fish such as large Barb species

Reading from this post, I would return the pleco (

Pterygoplichthys pardalis

), the loaches and the 'lobster'.

[danielle's tank]

ok thank you i will do the water change today when i am done work. i hope it is not the botia but i dont really see their interactions since they never come out when i can see them. i remembered yesterday a friend of mine once mentioned a friend of her moms that lives in a village not far from here, she said this lady has a room full of fish tanks, i am hoping to find out if she might like my botia as i really dont want to take them back to the lfs.