Re: Sick goldfish - red streaks in tail and slight swelling
#3
Very sorry to read about this, especially as he looks a lovely fish (very similar to my own one - RIP).
What you're describing in terms of not getting up to swim around, then swimming fast, behaving as though he's in pain, the red streaks/bump, all sound very much to me like the consequences of impaired water quality, most likely high nitrates. The fact that this has returned after treating him with the medication which you have (bacterial/fungus/finrot type treatment) suggests this all the more.
When I read what size your tank is and that there are 3 goldfish in it, it seems as though that's where the problem lies - read this article:
http://injaf.org/care-and-information ... t-size-tank-for-goldfish/ What happens is that the toxins - ammonia produced by the fish and which then converts to nitrite and nitrates - build up in the water and, in a tiny tank like yours, happen all the more quickly. Any level of ammonia or nitrite, and nitrates more than 20ppm (or more than 20ppm above whatever they are for your tap water), is toxic to fish, and result in them succumbing to illness (often chronically) or death, with the weakest succumbing first.
What I strongly advise, for the sake of this fish and before the others follow by succumbing to an illness to, is for you to do:
* daily water changes of 50%, replacing with dechlorinated water [Seachem Prime would be the best dechlorinator in this instance, as it helps detoxify ammonia/nitrite/nitrates for 24hrs following its use]
* buy a liquid-based (not paper-based) test kit, to be able to monitor ammonia, nitrite and nitrate levels daily - if there is any level above what I describe above, then do more frequent water changes to reduce that (eg 2 x 40% water changes per day rather than 1 x 50% water change)
This will be more beneficial than treating further with medication - try it and see, as you ought to see the benefits starting almost immediately.
However, what is most important is for you to upgrade the fishes' tank to a larger one - something like the Fluval Roma 240 litre tank is just about big enough to house 3 goldfish, and its benefit is that it's a long tank for the water volume which is what goldfish need. Alternatively, if they're all common/comet goldfish, they are actually better suited to ponds if you know of anyone with a pond. Very importantly, when you do upgrade the tank, make sure that all the filter media (sponge, foam) with the beneficial bacteria built up on that is transferred into the new filter, otherwise the filter cycling process will start all over again.
Hope this helps but keep us posted in how things are going. Best of luck!