# Zebra Danio getting skinny



## Sirkavu (11 Aug 2020)

Hi Everyone,

Hope you’re keeping safe!!

Start with My tank:
*Tank *Juwel Rio 180l
*Light *MultiLux LED | Kelvin 9000/6500 | Lumen 5290 | ON for 6h a
*Pump *Juwel Ecoflow 1000l/h
*Filter *Bioflow M Original
*Temp* - 24-26c (30/32 These last super hot days)
*Water* - London Hard water
*Fertilization* - EI Method
*CO2* - I use liquid CO2 Easy Carbo 3/4ml 6 days a week.

Sunday 50%WC
Prime to clean the water

*Plants*
Amazon Sword (Aquaflora)
Cyperus Helferi (Tropica)
Staurogyne repens Tropica (1-2 grow)
Alternanthera reickii (Aquaflora)
ludwigia repens (Aquaflora)

*Fish*
9 zebra danio
3 molly (1 is a baby)
4 golden Gourami
10 Amano shrimp
Cherry Shrimp  colony

So, since I last move my tank, just before quarantine, one of my Danio got very pale. Even tho pale and skinny, he was active and seemed normal until two weeks ago, when I found him dead in the morning.
Since then all seemed on until last week i saw another danio at the bottom kind of hiding. When I put food, he would always come up to get it. From 3 days ago I started to see him, or maybe another one, was losing weight and now I know it is, which makes me worried if there is something wrong in my tank or if it is the heat or maybe the fish has a disease?

My BBA has improved a lot from 2 weeks now, which was making me very happy as i had a problem before and had to clean very well the rocks and plants on my WC day.

What do you guys think the problem can be?

I haven't measured any tank parameters but I will get some kit to test it tomorrow when I am off work, but if you can help here I would appreciate.

All fishes seem happy even my Cherry Shrimp is multiplying well.




 This is the one that died. You can see how pale compared with the others.





  Here you seem the one that is now skinny


Thank you in advance


----------



## JeffK (11 Aug 2020)

They are a subtropical species, so I guess that the high temperature is doing them harm.


----------



## Sirkavu (11 Aug 2020)

Also to add that I have 3 Ottos. All of them happy and going around in their peaceful way 

@JK1991  Hm...I hope so. I will try and do something to keep the water fresh and around 24c.


----------



## JeffK (11 Aug 2020)

Biggest issue with warm water is that there's less oxygen. If you improve that, the remaining fish might survive.


----------



## hypnogogia (11 Aug 2020)

I don’t think we can conclusively say this Is heat related, as the temperatures were not so high when the last one died.
@Sirkavu, what temperature is your water? How old are the Danios? Have you made any changes to your tank routine or maintenance recently?


----------



## Dr Mike Oxgreen (11 Aug 2020)

I’ve currently got my filter canister sitting in a bucket of iced water.

Over the last hour or so the temperature of my 25 litre nano tank has come down from 29.1°C to 27.4°C, and there’s still plenty of ice in the bucket.

Once the bucket of ice has stopped cooling the tank, I have a few small plastic bottles in the freezer, into which I’ve put some salted water. In theory the salt should make the ice absorb more heat as it melts than it would with pure water, if my school physics is correct. I can float and re-freeze them in rotation.


----------



## Sirkavu (11 Aug 2020)

Hi @hypnogogia  I haven't done any changes at all tbh. Only got some flowers to se if the BBA would go away.

Danios I bought them in January but don't know how old they were at that time. Temperature is usually 22-24 only these very hot days have been 30+ with the heater off.


----------



## Dr Mike Oxgreen (11 Aug 2020)

30°C is going to be uncomfortable for a lot of fish, _especially_ danios.

As temperature rises, fish become more active and their oxygen demand increases.

At the same time, the solubility of oxygen in warmer water decreases, so oxygen availability decreases. Different species of fish can tolerate different minimum levels of oxygen.

This is a nasty double-whammy. Increased demand, decreased availability.

In your position I’d be looking for ways to reduce temperature, as I’ve been doing today. If you have an external canister filter, sitting it in a bucket of iced water really works - after about 3 hours my tank is down by 3°C, still with more ice in the bucket. You can buy bags of ice cubes in large supermarkets quite cheaply.

Alternatively, freezing small bottles of water and floating them will be quite effective too, and has the advantage of being renewable - you can simply keep rotating the bottles between the fish tank and the freezer.


----------



## Melll (11 Aug 2020)

Also, don`t have the tank lights on, lift the lid and get a fan blowing across the water surface.  Try to create a good water surface movement, use air stones in the tank, as @Dr Mike Oxgreen has said, freeze bottles of de-chlorinated water and put them in the tank as well.


----------



## JeffK (11 Aug 2020)

A fan aimed over your water surface also helps. 

You can also quite easily increase oxygen levels by lowering your water surface, so that your filter increases the movement of your water surface.


----------



## Sirkavu (11 Aug 2020)

You guys are amazing!!!

@Dr Mike Oxgreen  I won't be able to put my filter over ice as it is attached to the tank but definitely i will be bottles of iced salted water and put on the tank.

@Melll I will get the lights to be off, so there is no heat from it. They will get some light from the room as it is lit form outside light 

I have the filter tube (where water comes out) turned up so it creates bubbles of air to improve oxygen as well. I will get the water surface lower tomorrow as I am off and can take great care of my fishes!!

I was not prepared for this heat, at all!!!

The first Danio, maybe died from stress? I say this because the fish went pale after I moved the tank. So maybe I distressed him/her and never went to take a better care as I thought eventually would get better because was active.


----------



## Luketendo (13 Aug 2020)

Dr Mike Oxgreen said:


> 30°C is going to be uncomfortable for a lot of fish, _especially_ danios.
> 
> As temperature rises, fish become more active and their oxygen demand increases.
> 
> ...



Thanks, the bucket around filter trick is a great idea for when summer comes.


----------



## Sirkavu (13 Aug 2020)

So I tried to put the bottles on top, plus freeze some water from the tank and put it in also turned the light off and take some water so the oxygen grows.

All I managed was a 28/29, which is still better then 32/33. Today might rain so I am super hopeful that the house will cool down as well as the tank, if not, I will put all fans on the tank  hehehe

Again, that you all


----------

