F&C,
Several people (at least) who use this board regularly have shopped from Tri-Mar, myself included.
I received my fourth order from them yesterday and I have never had any problems with shipping. The fish are always well packed and are sent using a good courier company marked up as Live Tropical Fish - Keep Warm. Tri-Mar guarantee live arrival. You will need to be at home to receive delivery as they must be signed for but Tri-Mar will arrange a convenient delivery day. The fish are double bagged and packed in styrofoam containers and then boxed. A heat pack is put inside the lid of the container to help keep them warm. You will find instructions on acclimatising the fish in with them (along with your credit card reciept), you will need to follow them carefully as the fish will be more stressed than those you would buy locally due to the longer time in transit. Basically you just need to take a bit longer to let the temperatures equalise and spend a bit more time slowly mixing your tank water into the bag to let them adjust to your water parameters. Also NEVER put any of the water from the bags into your tank, the fish have been in there with no filtration overnight and there will be a build up of fish waste products.
Monty (the owner) has the attitude "We never ship fish which we personally would not be happy to own" as he and his staff have spent time building up a good reputation and don't want to lose it. I can attest to that as all of the fish I have had from there have been as described on the web site and of very high quality. I have never had any disease problems with the fish (but you should still quarantine if possible).
Tri-Mar have enabled me to get fish which I have not seen at my Local Fish Shops or have only seen on rare occasions. Also their pricing is very good compared to round my way (London) - for example I saw chain loaches at a shop here at £16.95 each, Tri-Mar have them at £6.99, another local shop had Lyretail Killies at £15 a pair, Tri-Mar at £6.50. Obviously the overheads are cheaper in Cornwal than in London
Hope this helps, if you need any more info ask away. Monty sometimes pops up here as do a couple of his staff.
Eddie
I too use Trimar and have found them great, i will definately use them again 
Buying fish from Trimar has saved me over £50 on prices in local shops ! (and thats with the postage 
