New tank, bad smell and tiger barbs dying, water tested good

[Wadido]

I’m a new tank owner, as you see tiger barbs are dying one by one over 3 day period. Water doesn’t smell so good. Should I refresh some of the water? Concerned, I have 6 gourami,s, 2 paste blues, 2 orange and two larger ones I can’t remember name of. One spotted Medusa Plecko, one smaller Plecko one smaller sucker.

 

[fluttermoth]

Hi there, welcome to the forum

Water that smells bad is not a good sign; a healthy tank might have a slight earthy, composty smell, but it shouldn't be strong or unpleasant. Do a large water change (by 'large' I mean at least 50%, making sure the new water is warmed and dechlorinated).

I'm guessing you didn't cycle your tank before you added fish? How big is the tank, and can you post the actual numbers from your tests, please?

 

[Colin_T]

Can you post some pictures of the sick fish and any fish you can't remember the name of?

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In addition to Fluttermoth's questions.
How long has the tank been set up for?
Do you have a filter and if so what is the brand and do you run it continuously 24/7?
How often are you feeding the fish?

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If the aquarium is new, then you only want to feed the fish a small amount once every second day for the first month. You only want to give them a small amount of food and they should eat it all within a minute. Any uneaten food should be removed from the aquarium to prevent ammonia building up.

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Get a clean bucket and only use it for the fish. Get a permanent marker and write "FISH ONLY" on the bucket. Don't let anyone use the bucket for anything except the fish.

You should change about 75% of the tank water about 4 hours after feeding the fish. Make sure any new water is free of chlorine/ chloramine before it is added to the aquarium. Fill your fish bucket with water and add dechlorinator, then aerate/ circulate it for 30minutes before adding it to the tank.

If you don't have an airpump to aerate the water, get two buckets and fill one with water and dechlorinator, then slowly pour that into the second bucket. Then tip it back into the first bucket. Do this 10-12 times and it should mix the dechlorinator with the water.

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Aquarium water should not smell. If it does then stop feeding for a few days and do a 75% water change every day until it no longer smells. And get the water tested for ammonia, nitrite, nitrate & pH, then post the results on here.

 

[Jordan_Deus]

Does your tank smell like sulfur? If so that may be anaerobic bacteria building up in the substrate... If that's the case, I recommend using a gravel vac to clean the substrate. You will see small bubbles coming out of the gravel into your gravel vac. If the tank smells of sulfur, there's probably a very large build up of it. So when you clean the substrate remove the fish and place them into a bucket, and perform a large water change (50% or more) before adding the fish back into the tank.

Please note that assuming the tank isn't heavily planted or doesn't have some other way for the substrate to be aerated, you need to stir up the substrate weekly to prevent build up of anaerobic bacteria.