All my fish at top of the tank!?

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Aquarium Advice Freak
Aug 7, 2006
San Antonio, Texas
Well I had an odd past hour. This morning everything was fine and dandy dosed my plants, fed the fish and dropped in 2 ghost shrimp from my 10gal(live food for the eel) then about 6pm i notice a few tetras swimming at the top of tank(all my fish are odd ball ground level lovers) then more and more and finally my gold algae eater, eel and shrimp have all taken up to swimming surface level. I freaked out did a 75% water change and they seem to be back to normal. Any idea what this may have been? the water grew steadily cloudier as the more fish grouped at the top
What size tank? What are your test levels? Sounds like an O2 problem to me? What kind of filter any airstones etc.?
29 gallon tank, no current tests atm aquaclear hob 150/30 and currently a whisper 10i as an extra to help clear it up. only 1 airstone hooked up to my Co2(hasn't been active since yesterday morning)
tank has been up for about a month now(was seeded from the 10gal and fish slowly added) high light lowly planted with the plants listed in info
i have tested it just ment no current one as the last testing was done prior to these sudden water changes, everything has been nice no ammonia very few nitrates were in right around 10

aside from that sudden change things seem back to normal for the night, any idea what could have caused a sudden O2 issue? only thing i could have thought of would have been a large co2 dose but there wasnt any added today
How much surface aggitation? Not sure if the lights were on or off, but plants use O2 at night, and the O2 in the water can get pretty thin at night if you don't have surface aggitation in a planted tank. For a low plant load, that shouldn't affect it though, and if you have a low fish stocking, then it shouldn't be the problem. It's strange though. Was there anything else that might have been done out of the ordinary? Also, for adding the ferts, how much did you add? Do you add it all in one spot or spread it around the length of the tank? Could the fish have gotten into a pocket of ferts? How much circulation in the tank? Just other thoughts to see exactly what you did.
there is a moderate amount of surface aggitation, my cabomba and filter media stir up and spread around the water coming out of the filter(fliter bags make it splash out of the filter and my cabomba sways around the top to spread them). as for ferts today was strictly a cap of flourish excel in the am spread over the top of the tank. lighting was on while all this happened 2x65watt after the water changes i turned them off. really the only crucial change was the addition of a few new ghost shrimp snacks but i can't imagine 2 ghost shrimp suddenly sucking up all the o2. as for a pocket of ferts perhaps but i think this would have happened 10 hours ago, not after the ferts were added and lighting had been on for 10hrs.

It literally happened in the span of 30 mins after i noticed the first of my tetras hanging around the top of the tank. i had spent most the afternoon watching the tank because ghost shrimp are quite interesting imho. saw a few up top thought nothing of it, turned away walked by saw the GAE and eel up at surface and promptly did a massive water change(left the filter going thinking it may be o2 so there was about a 5min period of a 10inch waterfall before the water was re-addded)
Sounds like everything should be just fine then. I don't see anything that would have caused it. As for the Excel, it's not really a fert. It's a carbon suppliment. When you said ferts, I was thinking nitrogen, phosphate, and potassium, or traces like iron, magnesium, etc.
temps stayed right around 77 a bit hotter when i did the change as my faucet water didnt have too much time to cool but peaked at 79-80 maybe. 78-80 is about average for my tank though as my apt gets nice and hot.

Lonewolfblue i do use ferts(flourish,nitro and potassium) but yesterday the only thing to add was excel
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