Unexplained Deaths In Tank

[dubgirl]

Hi, i hoping someone can help me. I have a juwel rio 180 tank that has been set up for approximately 8 months. I cycled the tank and it currently houses 6 shrimp, a bristlenose, 2 bengal loaches, 5 dwarf neon rainbow fish and 10 platies. I have had a bit of problem with algae, but now seem to have that under control. In the last two months, I have lost a platy, a rainbow fish and a shrimp, but I dont know why. There is nothing on the dead fish such as marks, sores etc and no evidence of anything like white spot, the other fish and shrimp appear ok. i do weekly water changes of 15-20% and regularly clean the filters in old tank water and change them according to juwels recommendations. At the most recent water change on monday I tested the water with the following results
ammonia - 0.1mg/L
Nitrite - 0.1mg/L
Nitrate - 12.5 mg/L
PH - 8.5

The testing kit is an interpet one, liquid water test. In the last few days, i have noticed that some of the fish, not all will hang about the surface of the water, but this is not consistently. if anyone has any suggestions I would be grateful thanks

 

[Gilli]

Your ammomia and Nitrite readings should both be 0. Are you overstocked or over feeding? Do you hoover the gravel well when you water change?

I would up the water changes, cut down on feeding and increase aeration until both readings are 0.

 

[gaz gun man]

how often, and how much filter media do you change? How often do you clean your filter media?

your ammonia and nitrite are high hence the fish at the surface of the water.

Have you tested your tap water for ammonia?

 

[dubgirl]

Hi thanks for the replies. With reference to the filter media, I clean the sponges about once a month. there are 6 in total and I do several at a time, rather than all in one go, I read someway that it was better to do it like that. I replace the sponges approx every 6 months, which is the juwel recommendation. I have not yet tested my tap water, but intend to do so. In terms of aeration there is an air stone in the tank, I had turned it off as i was led to believe that it drives oxygen out of the water, however last night i turned it back on again and I have to say that currently as I type there are no fish hanging at the surface. I intend to cut down on feeding, would once a day be enough? Will also try to up water changes to twice weekly.

 

[gaz gun man]

once a day is more than enough.

I normally feed my fish once every other day and its normally gone within a minute (its reccomended that they eat it all within 2 minutes though) A fish can happily go for about a week without food, so a small amount once a day or everyother day is enough

An airstone creates bubbles at the surface which allows oxygen to enter the water (I cant remember the exact cycle that takes place but thats basically right) so its best to have one, or have your filter outlet aimed towatd the surface to break the surface tension to allow for the gaseous exchange.

Personally, I dont think the sponges should need changing after 6 months, a year might be better IMO.