fish [ black eye fish] jumping out of water again and again

[neha]

There is some problem with my water quality and so yesterday i did 100 % of water change yesterday. I am having an aquarium tank with 5 fishes in which two of them are koi fish and two are gold fish and a black eye fish . the black eye fish has some tiny black small lines [ since last 1 month] in some parts of her fin which now has spread through to her body as well and i have tried some medicines like BACTONIL FW and GRANDFISH WHITE SPOT CURE but not got any successful results . as the water quality is bad the black eye fish continue to jump out of the tank but not falling on the floor .
. She always sits on the stones and is not much active but will be when its food time.
.all fishes are OK except one koi fish which has clamped fins and one goldfish with torn fin / tail . Since i have only 1 year experience with fishes i don't know what to do .i don't have any special equipment like water test kit .

as my tank was becoming more dirty I did 100 % water change[ full tank and gravels ] but have not added any medicine in the tank just aquarium salt .

now the black eye fish and with two other fish seem to have red and torn fins and so i moved them in a separate tub with an oxygen pump and a medicine called BACTONIL FW [ because i think that they might have fin rot and that medicine has once cured fin rot in my koi fish . but the black eye fish is continuing to jump in the tub trying to come out of water so i have covered the tub with a net .


i used to change the water from the tank after every 2 weeks and used to add aquarium salt . But now it has been a month but no improvement is seen . please kindly suggest something .


tank is of 25 liters
the black eye fish is of 4 inch or10.6 cm [approximately]
I don’t know whether my filter is biofilter or any other and if is then I even don’t know the level
the fishes get oxygen through the filter itself so there is no need of air pump

 

[qclabrat]

Neha,
I suggest keeping your posting on one thread to ensure you and we are on the same page. Opening multiple threads will not get you more responses. Please provide pictures of your setup and sick fish, narratives are useful but pictures will help us to not misinterpret your words.

 

[brokensword]

the torn fins can be attributed to fish overcrowding and one not getting along with another. I'm not a fan of adding salt, though there are some reports it helps with bacterial infections. As I noted in your other thread, your aquarium is far too small to have so many (and the kind) of fish. If I'm not mistaken, the red can be from ammonia burn, which comes with overfeeding/overcrowding.

Your fish don't get any O2 from your filter, only from the surface agitation a filter can provide. Same if you DID have an aerator except an aerator would probably help by causing more surface turbulence, which drives better water column aeration. Plus, aeration would help move even more water, which is a good thing. But imo, the first thing to do is increase the volume of the habitat, even if it means they ALL get their own separate aquarium. And even then, the koi are going to be a problem.