Is it really necessary to completely sterilize an aquarium

[ganesan]

I plan to keep about 7 adult discus in a 5x2x2 aquarium barebottom
Currently this aquarium is barebottom with some drift wood few anubias and a canister filter running for about 8 months. It has minimal fish just a dozen tetras, one pleco,few otocinclus. I just top off the water and do 30% wc every fortnight. The fish are fine. Now I am thinking of removing all these fish and just keep 7 adult discus fish with same driftwood and sponge filters and canister filter. Is it a must to wipe this tank clean with bleach before adding the discus or would it be fine to just wipe the rank clean,add fresh aged water and start the old canister filter with matured media that already existed in it and keep the old sponge filter.

[brewmaster15]

With Discus, there is often 2 ways to do things ..The way that is best for the Discus and the way that is best for the Hobbyists. No one can tell you which to choose..

It has minimal fish just a dozen tetras, one pleco,few otocinclus. I just top off the water and do 30% wc every fortnight. The fish are fine

How do you know that they are fine? internal worms can show no symptoms at all in one fish and be passed on to other fish. Fish can carry Mycobacterium (marine TB) with no symptoms until stressed and they then shed it into the tank. Cryptobia is a parasite that wide spread in fish and again can be carried without symptoms. The list really goes on and on. Your existing fish may be "healthy" but that doesn't mean they are fine to mix with your new Discus.

I am always very cautious when mixing other species with discus, very few pathogens are discus specific. I treat all fish species as possible carriers.

If you are planning on going this route I would remove the fish and leave the tank empty a few weeks. You can maintain the biofilter with clear ammonia until your get your discus..

I have to ask though if you are sure these current occupants are clean why not just leave them?

al

[seanyuki]

Cross contamination can happen when you mix any aquatic living things from different sources (even water) into the same tank. It can be fish, shrimp, snails, plants or sponges etc. The point of having a sterilize tank is not having anything from an existing tank due to cross contamination.

[ganesan]

Very interesting points. I guess some fish which are not discus like tetras plecos etc could have stronger immunity and may look healthy when in fact they may have some infection which we fail to notice. Like you say I think.its best to clean the whole tank with bleach and start again from scratch with all new sponge filters or bleach cleaned sponge filters, new airline tubes and new aerator stones and new python suction tube. I am sure bleach would kill all germs. Is it necessary to fill the tank with water add bleach and leave for a few days or just few hours and wash would suffice.

[ganesan]

Thanks yes I think with discus fish we should never take any chances.

[brewmaster15]

Very interesting points. I guess some fish which are not discus like tetras plecos etc could have stronger immunity and may look healthy when in fact they may have some infection which we fail to notice. Like you say I think.its best to clean the whole tank with bleach and start again from scratch with all new sponge filters or bleach cleaned sponge filters, new airline tubes and new aerator stones and new python suction tube. I am sure bleach would kill all germs. Is it necessary to fill the tank with water add bleach and leave for a few days or just few hours and wash would suffice.

I personally like to add it to the water and let it circulate but if the tank has been wiped down well a spray bottle of 10% bleach should work well enough... spray bleach .. cover tank to keep from evaporating for several hours.. fill and drain twice.. then air dry .
Al

[ganesan]

Thanks I thinking filling and draining it after a day would be the best choice

[seanyuki]

I do 1 cup bleach per 10g. let it sit for a couple of hours and then drain. Rinsing would be the most important part. Rinse thoroughly, fill again, add lots of dechlorinator, let sit. Drain. Rinse again. Air dry for a few days.