Sorry for the loss, That can be the problem when trying to slowly acclimate shipped fish.
Also like DrgRcr said, the synos will be much happier in a group. I love these guys since they are so active! They are slow growers though. I wouldn't worry too much about them being tiny. I think they have some sort of spins or bad taste. When I first got mine a couple of my mbuna grabbed the catfish then immediately spit them out and made "yucky" faces. The catfish were unharmed and since then the mbuna leave them alone.
Also like DrgRcr said, the synos will be much happier in a group. I love these guys since they are so active! They are slow growers though. I wouldn't worry too much about them being tiny. I think they have some sort of spins or bad taste. When I first got mine a couple of my mbuna grabbed the catfish then immediately spit them out and made "yucky" faces. The catfish were unharmed and since then the mbuna leave them alone.