tank wiped out!

[d0t]

Hello,
I've had a small-sized tank of guppy fry for about a month. It was simple setup, with just a sponge filter with aeration it. Went out one day and came back to find all the fry dead. The funny thing was in the morning, they were all alive but all swimming at the surface. What could have been the problem?

[vinz]

Swimming at the surface indicates they have problems breathing. They instinctively go to the surface because that's where they can gulp air or the O2 has higher concentration due to gaseous exchange with the air. Means their gills are not functioning well or there isn't enough O2 in the tank.

Unlikely to be the latter as you do aerate the tank.

So it's more likely to be gill burn due to ammonia or nitrite spike. Your tank is only one month old, so it is quite likely too. Searching the forum and web for "Nitrogen cycle" and "Tank cycling" for more info.

How often do you change water? Did you wash the filter? How do you wash the filter?

How much, how often and what do you feed? And how fast do the fries finish the food? Any leftovers?

[d0t]

well it's primarily my breeding tank..
I change like 30% of the water every 2 weeks. the filters hasn't been washed since then.. but i had it up and running for about a week before introducing the fry. I'm just curious. could it be that my air pump is somehow pumping in c02 or something like that

[d0t]

oh and if it is an ammonia or nitrate spike? could they die so fast? i mena they were alive at 8am? but all dead at 5 pm..

[vinz]

oh and if it is an ammonia or nitrate spike? could they die so fast? i mena they were alive at 8am? but all dead at 5 pm..

If I covered your mouth and nose, how long will you last?

[vinz]

well it's primarily my breeding tank..
I change like 30% of the water every 2 weeks. the filters hasn't been washed since then.. but i had it up and running for about a week before introducing the fry. I'm just curious. could it be that my air pump is somehow pumping in c02 or something like that

If you run the filter for a week without any ammonia source (i.e. fish waste, leftover food, etc), the bacteria colony will be very small... definitely not enough to handle a sudden comparatively larger load of fish waste and leftover food (if any).

Your aeration will be raise the CO2, but definitely not enough to cause CO2 poisoning at any scale.

I haven't raised fries in a dedicated tank before. Perhaps you should check with the other members on water change frequency for fry tanks. They would be a lot more sensitive then adult fishes.

[d0t]

no no, i'm pretty sure that fish would die quickly without oxygen. my point in asking that question was what would the ammonia and nitrate spike do to the fish....

[vinz]

Ok.. you didn't understand my earlier post. Ammonia and nitrite will cause gill burn, which basically damages the gills... hence the fish can't get enough O2.

I don't remember the biological details... search the forum/web for "gill burn fish".

[vinz]

Oh... and look up ammonia and nitrite poisoning too.

[d0t]

ahh good stuff. thanks!!