Fish dying for no apparent reason

[Sid]

Hi everyone,

So I decided to buy a fish tank about 6 weeks ago. I did the cycle and purchased 6 guppies, 2 weeks later. I then bought 4 platies and 3 small bristlenose the following week. Things then started to go downhill about 3 days after purchasing the platies and bristlenose. 1 guppy died, then a platy died the day after. They were both at the top of the tank with their mouths opening and closing at a rapid speed. I thought that these two must've been weak fish so I didn't change anything in the tank. Another 2 days went by and another guppy died. It was doing the same thing: opening and closing its mouth at a very fast rate on the surface of the tank. I got my mate over who tested the water for me. All was good except for the PH levels which were at 6.0. My mate said these were due to low oxygen levels in the tank, so, he let me borrow his aerator. We also put some coral bones in the back of the filter and put some "PH Up" in the tank as well. It has since been 3 days since this happened. Another guppy has died and one platy isn't looking too good. By the way, I have been feeding them once a day, and only today I fed them twice (with smaller food) and they all went berserk - even the sick platy. I have no idea what to do!!! Please help!

 

[V227]

I suggest that you slow down a bit. Your tank is still new and apparently chemically unstable.
I would conduct two 25% to 35% WC' s per week for a month until things eventually level out.
Note: IMO, not a good idea to use chemicals to alter the PH. The added limestone should be enough to buffer the water. Good luck.

 

[Upstate TBarbs]

They say that PH changes greater than 0.2 in a 24 hour time period will stress the fish out.

First of all, get this:

API Freshwater Aquarium Master Test Kit

Petco / Petsmart have the kit, as may your LFS. Shop around, I have seen this for anywhere from $23.99 to $34.99 local and online.

When your friend tested, what were the Ammonia, nitrIte, and nitr8 levels?

I also recommend the water changes. I did not see that you mentioned the size of the tank, but you should probably prep water a day or two in advance of your water change. By that I mean have it at a decent temperature for the fish, have it dechlorinated/dechloramined with Prime, and check the PH before it goes into the tank.

 

[Mebbid]

Without knowing the actual readings of the water we can't really say what the problem is. Like was stated previously, we need to know ammonia, nitrite, and nitrate.

 

[Toad]

And what size tank? 3 bristlenose is a hefty bioload, even with small ones.

 

[Sid]

Thank you everyone who has replied. It really means a lot to me having the fish community coming together to help each other out.

Everything in the water was perfect except the ammonia and PH - the ammonia was at 0.25 and the PH was at 6.0. Also, the tank size is 70 litres (18.4 gallons)

Thanks

 

[Upstate TBarbs]

Ok, based on the size of the tank, I'm thinking you are overstocked. Not sure what you have for a filter, but I guessed something like an Aquaclear 30.

This comes from AqAdvisor - Intelligent Freshwater Tropical Fish Aquarium Stocking Calculator and Aquarium Tank/Filter Advisor

 

[Coursair]

Thank you everyone who has replied. It really means a lot to me having the fish community coming together to help each other out.

Everything in the water was perfect except the ammonia and PH - the ammonia was at 0.25 and the PH was at 6.0. Also, the tank size is 70 litres (18.4 gallons)

Thanks

Ammonia is a fish killer.

18g is not a big tank.

Too many fish, added too fast.

1 BN Pleco needs at least 30g , I’d say return those. They are poop machines. They poop a lot more than they clean. They will starve in a new clean tank unless you feed them. If you want a type of suckermouth Cat ? Look at a Clown Pleco or once the tank is mature you could try Otocinclus. Or just add a Nerite Snail once your tank isn’t so new.
Algae Eaters don’t prevent algae. Don’t add them for cleaning. Only add them if they fit the tank and you like them.

Water changes. Don’t add any new fish. Get your conditions stabilized. Add plants.

I’m sorry you lost fish.

Research the fish you have. Research before adding any other fish. Stores will say anything to sell fish. Not all, but most.

 

[Mebbid]

At a 6.0 pH ammonia is not particularly dangerous to fish.

Looking at all of this I would say pH is your culprit. When a tank shows a 6.0 pH level that means the water is generally very poorly buffered.

To check whether the pH is the cause check your pH in the morning before the lights come on and at night before they get turned off. We need to make sure you aren't having wild pH swings.

Also taking a water sample to a LFS and having them check your dKh would be recommended.

 

[Sid]

Thanks everyone for your help I worked out the problem