Help! Why do my fish keep dying?

Why do my fish keep dying??
Tank

What is the water volume of the tank? 10g
How long has the tank been running? 3 months
Does it have a filter? yep
Does it have a heater? yep
What is the water temperature? 74f
What is the entire stocking of this tank? (Please list all fish and inverts.)
4 male guppies, 4 pepper corys

Maintenance
How often do you change the water? wkly
How much of the water do you change? 50%
What do you use to treat your water? prime, fluval aqua plus
Do you vacuum the substrate or just the water? both

*Parameters - Very Important
Did you cycle your tank before adding fish? it was a fish in cycle, but cycled now
What do you use to test the water? api freshwater master kit
What are your parameters? We need to know the exact numbers, not just “fine” or “safe”.

Ammonia: 0
Nitrite: 0
Nitrate: 30
pH: 8

Feeding
How often do you feed your fish? daily, fast once a wk
How much do you feed your fish? pinch
What brand of food do you feed your fish? tetramin tropical flakes
Do you feed frozen or freeze-dried foods? no

Illness & Symptoms
How long have you had these fish? all different dates (kept replacing)
How long ago did you first notice these symptoms? few days
In a few words, can you explain the symptoms? suddenly get tattered tails, then they die
Have you started any treatment for the illness? no
Was your fish physically ill or injured upon purchase? no
How has its behavior and appearance changed, if at all?

Explain your emergency situation in detail. (Please give a clear explanation of what is going on, include details from the beginning of the illness leading up to now)
My guppies keep dying. 3rd one today. I've noticed that they all suddenly get tattered tails and then they die. Sometimes it's chunks out of tail, others have shredded tails. What is wrong? My corys are acting weird and my other guppies are too.

 

My guess is the male guppies are fighting. Have you noticed them chasing each other?

 

My guess is the male guppies are fighting. Have you noticed them chasing each other?

A little, but not to the extent of killing each other

 

A little, but not to the extent of killing each other

If they're getting chased around all the time it will stress them out. Are there decorations they could be getting their fins snagged on?

 

Why do my fish keep dying??
Tank

What is the water volume of the tank? 10g
How long has the tank been running? 3 months
Does it have a filter? yep
Does it have a heater? yep
What is the water temperature? 74f
What is the entire stocking of this tank? (Please list all fish and inverts.)
4 male guppies, 4 pepper corys

Maintenance
How often do you change the water? wkly
How much of the water do you change? 50%
What do you use to treat your water? prime, fluval aqua plus
Do you vacuum the substrate or just the water? both

*Parameters - Very Important
Did you cycle your tank before adding fish? it was a fish in cycle, but cycled now
What do you use to test the water? api freshwater master kit
What are your parameters? We need to know the exact numbers, not just “fine” or “safe”.

Ammonia: 0
Nitrite: 0
Nitrate: 30
pH: 8

Feeding
How often do you feed your fish? daily, fast once a wk
How much do you feed your fish? pinch
What brand of food do you feed your fish? tetramin tropical flakes
Do you feed frozen or freeze-dried foods? no

Illness & Symptoms
How long have you had these fish? all different dates (kept replacing)
How long ago did you first notice these symptoms? few days
In a few words, can you explain the symptoms? suddenly get tattered tails, then they die
Have you started any treatment for the illness? no
Was your fish physically ill or injured upon purchase? no
How has its behavior and appearance changed, if at all?

Explain your emergency situation in detail. (Please give a clear explanation of what is going on, include details from the beginning of the illness leading up to now)
My guppies keep dying. 3rd one today. I've noticed that they all suddenly get tattered tails and then they die. Sometimes it's chunks out of tail, others have shredded tails. What is wrong? My corys are acting weird and my other guppies are too.

What do you mean by the cories are acting weird? If its sudden like that it really seems like fighting between the male guppies. Having 4 males together sounds like they would fight a lot

 

If they're getting chased around all the time it will stress them out. Are there decorations they could be getting their fins snagged on?

Not really, all live plants and decor doesnt seem sharp. How can I stop it if it is bullying?

What do you mean by the cories are acting weird? If its sudden like that it really seems like fighting between the male guppies. Having 4 males together sounds like they would fight a lot

Well the corys are a different story. They haven't died, but one is, seemingly, recovering from being very lethargic and it seemed like skin was peeling on his head. The other ones are pretty good, just sometimes seeming lethargic/inactive but I understand that to be their nature?

 

Not really, all live plants and decor doesnt seem sharp. How can I stop it if it is bullying?

Well the corys are a different story. They haven't died, but one is, seemingly, recovering from being very lethargic and it seemed like skin was peeling on his head. The other ones are pretty good, just sometimes seeming lethargic/inactive but I understand that to be their nature?

Unfortunately you're likely going to have to rehome/return fish. The key to fish not bullying each other like that is really a good compatible stocking list in a proper size tank for the fish you want.

At the very most I'd do two male guppies in a 10g tank, honestly I'm really not the biggest fan of guppies in a 10g just because some can be fiesty like that. Endlers are usually a better choice because they're a little calmer and more docile in smaller tanks.