Hello/Help me please!!

I have a 110 litre aquarium and a number of fish (will list at bottom) I recently added four female guppies and two male.

Almost as soon as they were in one or two of my three black widow tetras picked out one of the male guppies and started attacked him, biting pieces from his tail. (I had three black widows for a long time then two died, I replaced them with these two newer ones about 2 months ago).

The older black widow was not involved and I couldnt tell if it was one or both of the newer ones so I have quarantined them both.

Unfortunately, by this time the other fish noticed the injured guppy and all hell broke loose, as you can imagine.

I still have the two quaruntined (how do you spell that?)and was looking for some advice on how to proceed.

I am concerned that if I reintroduce the two bad boys they will simply work their way through the remaining guppies. Was the guppy weak in a way only the the other fish could sense, triggering the attack?

Any help you can provide would be very very welcome!!

Fish owned: 3 Silver (Bala) Sharks, 3 flame tetras, 3 silvertip tetras, 3 black widow tetras, 2 cardinal tetras, 1 gold spotted plec, 1 red tailed black shark, 1 ram, 1 kribensis, 6 sorry 5 guppies.

Male guppies are the whipping-boys of any fish tank, unfortunately - any aggression is usually directed at them because of their large, colourful tails which means they can't swim away as fasy as they often need to. I'm frankly surprised that your Kribensis didn't beat the Black Widows to it - I once lost half a dozen guppies to a lone Krib in the space of ten minutes!
Black Widows are usually fairly peaceful community fish, but like any animals, some are naturally more aggressive than others, and I have witnessed many a nipped fin from a pugnacious widow. They tend to be better in groups of six or more, as the aggression tends to be contained within the group rather than directed at other fish in the tank, so maybe you could try adding a few to see if this helps the situation. Otherwise, my only suggestion is to take the guppies back to where you bought them and replace them with fish that are less of an easy target.
Hope this helps,
Marc

yeah black widow tetras suck, they are known to be nippy to small fish, and they are not even good looking