Simply Koi and More Koi

Never put the needle back into an antibiotic bottle once used on a fish, bacteria from the fish will transfer to the inside of bottle and contaminate that and the rubber membrane and can live in the neck and you can cause all kinds of contamination problems
you can use the syringe again as long as you have not drawn back on the fluid after its been in the fish but change needle every time

or if you have a limited supply of needles draw more antibiotic then you need say enough for 3,4 or 5 injections in one go, then you can use the same needle but only on the same fish
Never. ever, put a used needle anywhere near your bottle of antibiotic

its always worth mentioning never allow air into the bottle, an antibiotic bottle is designed to pull a vacuum as you gradually remove all its contents so as the level drops and it becomes harder to draw off it, don't be tempted (as I've seen some do ) to put sideways pressure on the rubber seal with the needle allowing an inrush of atmospheric air to make it easier to draw off the bottle.

you should not need me to tell you what just happened if any of you did this in the past or make a practice of it

Duncan,

I've seen people prevent the vacuum forming by pulling back the syringe to the same amount as they intend to draw off before inserting the needle into the bottle and then "injecting" that air into the bottle before drawing off the antibiotic. The bottle initially becomes slightly pressurised before the antibiotic is drawn off and the pressure in it returns to normal afterwards.

Assuming this is done with a new syringe, so that nothing except air can enter the bottle, do you think that's a good idea or can you foresee any hidden problems?

trouble with that Syd is your drawing all kinds of crap into the syringe could be airborne, mould or fungus spores, bacteria etc, there's not way of telling what you have introduced into the vial

The hygiene involved in putting antibiotics into a sterile bottle so the contents are pure and sterile as can be, is incredibly complex the companies have to go to enormous lengths to make sure no contamination enters the bottle they use autoclave or a form of, Irradiation, ozone you name it they use it. Once done they have to load and secure in a sanitised environment its incredibly complex, its not like a factory bottling tomato sauce or a jar of pickled oinions out in an open factory <grin> and even they don't claim 100%
then after all this along we come a dump a load of atmospheric air in the bottle, se what I mean?
like I say the bottles and seal were designed to pull a vacuum and if you cant get the last bit out leave it there. That's said if there's only a ml or 2 left and you intend to use it straight away I dare say a little air under this circumstance wont make the difference

dunc

Thanks Duncan, that makes perfect sense.