Red Clot patterns on my fish please help!!

Hi

This is my first post, but a real urgent one. I have had my fish for about 4-6 years now, just recently they have become little inactive and uncomfortable.
Today i noticed red5 clottings on their body. I dont know what it is , but please help me out with this.

This is how they were earlier: http://www.youtube.com/watch?v=0TTKbI3Tvds&feature=plcp

This is what i noticed on them today:


Symptoms:

Inactive
Red stain on body
Trying to get something off their body they rub around on gravel and other objects
Loss of appetite

What i have at home:

1. Malachite green
2. Anti itch

Please help me out with this, i really dont want them to die there are not good vets near to my house. Currently i have put 2 caps of malachite green in my aquarium. you can check out the size of aquarium etc here: http://www.youtube.com/watch?v=0TTKbI3Tvds&feature=plcp


Thanks in advance
Rajdeep Rath

1. Well the size of the tank is: 56 inched wide and 18 inched in height. - holds about 9 buckets of water
2. i have just replaced 3 buckets water last week
3. the second koi died 2 months ago so now i have 3 fish in total
4. i have a custom filter for my aquarium that i made myself you can see in the video posted below
5. i clean normally once in 4 months
6. i feed them a food called Tetrabits (2-3 times a day)
http://www.tetrafishasia.com/tetra/...seite=7&group_id=205&group_2_id=11&lang_id=30

7. This is my aquarium now: http://www.youtube.com/watch?v=kKhp9QXcGOI

Please help me

1. I did a 3 bucket water change 2 days ago , should i change again? will it be safe ??
2. I have 2 air pumps that i have attached to my filter to make it like a water pump + aeration:
See the filter here: http://www.youtube.com/watch?v=DbauJDhFvyU

3. Why is the body getting Red and why are they trying to get something off their fins they keep brushing off fins after some time. Could it be a parasite issue ??

I see... thank a lot. So i was thinking ammonia poisoning can only happen after long time of no cleaning. I dont have a kit (its not even sold here locally) But i think you might have correctly gauges the problem. Please tell me how to proceed from here.

1. Normally the pump keeps running 24 h a day, and i clean the sponge once in a month
But this time due to some problems the pump we off in between for long periods. Perhaps this could have triggered it.

2. If you suggest that i get the whole aquarium cleaned i will get that done in 2 days. Or if you think just changing water is enough i can do that myself in frequencies.

3. Is there a way to use something at home to gauge ammonia levels ? Perhaps i can buy litmus paper from shop and keep with myself.

4. because the tank is big i avoid full cleans every month - also to avoid chlorine.

Yes i use a anti chlorine solution. In these 6 years this is the first time this has happened just a month after aquarium cleaning. i shall change 50% to 70% water today itself and check out the results. I am very grateful to you for helping me out. If everything works out , i shall thank this community site in my own way thanks again. going to change water now.

Also one question, My koi has a keen way to asking for food if you saw the first video. It looks so Doggie like behaviour that if he does that to anyone they go and feed him out to affection. So even when am not present they are fed, by everyone who comes near the aquarium, this amounts to being fed 4-6 times. should that be bad for the fish too ??