one neadle is not ideal most chemist will sell neadles for insulin use and one injection wouldnt help realy any way. temperature could do with been higher than 19 also for antibiotic use, but untill he finds out which kind of bacteria he has i wouldnt suggest turning temp up as it can make the outbreak worse
he neads to find the course of the problem, why they have got the sores in the first place. acriflaven is a good product to use in a pond were there is bacterial issues and i would suggest giving some like paula renaulds a ring at lincs fish health, she is very good and will advice your customer on the best route of action and you can also send her swabs and she will test for which bacteria is present and which antibiotics are best
her number is 01205 723413
do you think he can et on top with injecting
MARC HAS YOUR CUSTOMER INJECTED A FISH BEFORE AS A JAB IN THE WRONG PLACE ITS GOODBY FISH