Sterilizing An Aquarium?

[Untouchablejen]

So I originally had bought a small tank, and 2 koi afterwards. After realizing they needed a bigger tank I bought a 25 gallon aquarium. Everything was fine for 2 weeks until I bought 3 small goldfish. After a day I started seeing one of the new goldfish acting strange then white stuff accumulating on his body, took him out and seen his fins were disintegrating, he died a day later.

I am now treating the aquarium and fish with a general disease cure/remover the fish store told me to use. I put in 5 tsps let it cycle 24 hours, siphon the gravel let that cycle 24 hours then repeat that 2 more times. I'm on the second treatment today and a gold fish that wasn't showing any signs suddenly died. One koi is absolutely fine, while the other his top fin is disintegrating and a hole has developed on his body where this has happened, he also poops white clear stuff and usually has some hanging from his anus.

I'm new to this, about a month into it and I'm not sure what to do... The last goldfish was sick(blood under the skin around mouth and fins) but he appears better and my other koi seems very very healthy...I'm anticipating only the healthy koi to make it at the end of the treatments.

How do u sterlize the aquarium and all the decorations and plastic plants??? I'm just going to throw out the gravel.

 

[BerryAttack]

the koi is too small for the tank, and needs a very large pond.
 
the reason you are having all of these issues are because you never cycled your tank. there is ammonia, nitrite (or nitrate ... always confused on the two sorry) are affecting you fish... 
so now you must do a fish in cycle.. look on the site and it'll have all the info... and also the white poo can indicate that you have an internal parasite... and the fins deteriorating is fin rot.

 

[Ninjouzata]

Indeed, the koi and even the goldfish are not meant for a 25g.
Koi absolutely need a pond, and it depends on what kind of goldfish you have on what they'll need, if they're fancy then 30g for the first and 15g for each additional fancy.
If it's a comet then it'll need larger, I'd think also a pond like the koi but have seen people keep them in larger tanks so really not sure.
 
Here is an article on cycling: http/www.fishforums.net/index.php?/topic/421488-cycling-your-new-fresh-water-tank-read-this-first/
Keep in mind that is fishless and not fish-in, but it will give you an idea of what is going on.
 
Sorry you're having a bad start, and welcome to the forum!

 

[Skies]

Indeed, the koi and even the goldfish are not meant for a 25g.
Koi absolutely need a pond, and it depends on what kind of goldfish you have on what they'll need, if they're fancy then 30g for the first and 15g for each additional fancy.
If it's a comet then it'll need larger, I'd think also a pond like the koi but have seen people keep them in larger tanks so really not sure.
 
Here is an article on cycling: http/www.fishforums.net/index.php?/topic/421488-cycling-your-new-fresh-water-tank-read-this-first/
Keep in mind that is fishless and not fish-in, but it will give you an idea of what is going on.
 
Sorry you're having a bad start, and welcome to the forum!

Completely agree about the tank sizes, if it's a Comet it will need a 75 Gallon tank or larger, just for ONE comet. I recommend the poster reads your link regarding cycling, it's very important... if they are fancy goldfish, they won't survive a 'fish in' cycle.
 
All of the fish should be rehomed or taken back as soon as possible..

 

[DerpPH]

Never sterilize an aquarium! It kills All beneficial bacteria! Get a pond for the fish! They dont deserve to be in a really tiny tank compared to how big they get!

 

[IonaMcCluskey]

the white stuff accumulating sounds like a fungus due to bad water conditions
the fins disintegrating is due to bad water conditions
blood around the eyes/gills can be oxygen deprivation common in bad water conditions
 
you dont need to sterilize your tank you need to seriously reduce the amount of fish you have in your tank to improve your water condition
 
as you mentioned above, fish poop, this poop causes polution in your tank. this means your fish is constantly living in a polluted enviroment.
the following figures are not exact, just a way to explane in layman terms.
say 1 inch of fish produces 1 unit of pollution a day
 
1x1inch fish in a 25g tank          1x2inch fish in a 25g tank          7x1inch fish in a 25g tank
 
1unit pollution per 25g                2unit pollution per 25g              7unit of pollution per 25g      ON DAY ONE
2unit pollution per 25g                4unit pollution per 25g               14unit of pollution per 25g    ON DAY TWO
 
see how the pollution rises in accordance with the amount of fish you have in your tank?
 
this pollution equates to you taking a dose of posion, how much posion can you take before you fall ill and die? the higher the dose the quicker you succum.
 
fish also need to breathe, they breathe dissolved oxygen in the water. the more pollution you have the less dissolved oxygen you have. the size of your tank/ surface area limits the rate at which the oxygen is absorbed (there are ways to improve this but lets keep it simple for now). if you put one man in a sealed room with a 8hr oxygen supply, he will last 8hrs, if you put 2 men in there they will only last 4hrs. same goes for fish in a tank.
 
also we all know if a man is confined to bed for extended periods of time his muscles will atrophy, he will develope bed sores and all other ailments which leaves his body in a weakened state making him more subseptable to posion and lack of oxygen. do you expect this man to live?
 
fish need room to swim freely in order to exersise, in an over crowded tank this is not going to happen.
 
you didn't mention a filter or air pump so i'm going to assume you don't have these, in which case i would recommend ONE gold fish in your 25g tank, even altho it may only be a 1inch fish at this time it will have the potential to grow to approx 10 inch or more.

 

[Untouchablejen]

I should have gave more information, I have a filter that's for a 30gal tank and I have a air bubble thing. I use water conditioner everytime I took out water, including the first time I set up the tank, I also used beneficial bacteria solution when I first set it up. The reason why I want to sterlize the tank is because all these fish will most likely die and I am going to buy a heater and get tropical fish.

One koi is most likely going to live because he is very healthy but I will probably give it away. I also have an algae eater, could he be sick too?

 

[Skies]

I should have gave more information, I have a filter that's for a 30gal tank and I have a air bubble thing. I use water conditioner everytime I took out water, including the first time I set up the tank, I also used beneficial bacteria solution when I first set it up. The reason why I want to sterlize the tank is because all these fish will most likely die and I am going to buy a heater and get tropical fish.

One koi is most likely going to live because he is very healthy but I will probably give it away. I also have an algae eater, could he be sick too?

The issue is not the filter you use, or the bio-load at this point, it's the space you have and how big your fish are going to get (which not only has to do with bio-load, but healthy growth and longevity of your fish)... you could use a filter for a 100g tank on that thing and it won't solve your problem... all of your fish will die if they are not re-homed... however, a single goldfish may be able to live in your 25g, although 30g for 1 goldfish is preferable, unless it's a comet, then it will need no less than a 75g.
 
Allow me to help you visualize your issue...
 
Koi Get VERY BIG:

 
 
Goldfish can get big too, store bought veiltail compared to a full grown specimen:

 
You see, they cannot be kept in that tank, they won't survive, as a loving and responsible pet owner, the best thing you can do is give the koi away, or sell it, and then re-home 2 of your 3 goldfish... or buy a much bigger tank, that I am sure at the moment is out of your budget.

 

[IonaMcCluskey]

what i was trying to say is that i think your fish bad health is coming from bad water conditions not a desease or anything like that, so your tank does not need sterilizing, will not benifit in any way.
it doesn't matter what kind of fish you keep, if they are not in good water conditions they will become unhealthy, so your alge eater will eventually succum aswell if you over stock the tank again.
i'm glad to hear you are going to rehome the koi as these fish really do get to large for a tank.

 

[Untouchablejen]

Ok I understand I need a bigger tank, but they will most likely all die except for one koi which I will give away. How do I sterlize the tank and decorations? I do not want the next fish I get to get the disease because then tank still had it
And my 2 koi were in amazing health till I brought home the goldfish. Day 1 one was sitting on the rocks at the bottom never eating and j realized he had crystals on him, the other had black dots on his body...which now more are developing but he seems to be in good health.

One koi is still in amazing healthy while the other appears to have fin rot? Or ick? Poops out clear strings.

And the last goldfish remaining was sick, blood pooling on mouth and fins is gone how, but black spots keep appearing.

 

[Skies]

Ok I understand I need a bigger tank, but they will most likely all die except for one koi which I will give away. How do I sterlize the tank and decorations? I do not want the next fish I get to get the disease because then tank still had it
And my 2 koi were in amazing health till I brought home the goldfish. Day 1 one was sitting on the rocks at the bottom never eating and j realized he had crystals on him, the other had black dots on his body...which now more are developing but he seems to be in good health.

One koi is still in amazing healthy while the other appears to have fin rot? Or ick? Poops out clear strings.

And the last goldfish remaining was sick, blood pooling on mouth and fins is gone how, but black spots keep appearing.

Your tank was overstocked and it sounds like it was poor water quality that caused your issues, on the other hand it could have been coupled by one of the goldfish you brought home possibly having an existing health issue that contaminated your tank. After you re-home all of them, if you are really worried about it, you can scrub the tank down really well with vinegar, rinse it real well, and set it out in the hot sunshine to dry.