Oil Slick?

[Paul70]

on the surface of my water there is what can only be described as a sort of oil slick. is this normal?

also, one of my female tiger barbs has been simply sitting in one corner of the tank under some cabomba that has grown extensively in 1 week and. she has been seemingly panting a little. however today I have got up expecting to find her dead and she is quite happily swimming about again.

perhaps a temporary illness or could she be pregnant?

 

[BIG BAD BARRY]

The oil slick is normally from food that is on the surface before sinking or being eaten.
As long as the filter output is disturbing the surface, it should be gone quickly.

 

[Gilli]

The best way of seeing exactly if anything is wrong in your tank and the first thing you should do if any fish dont look right is to test your water quality. What are your water stats?

 

[Paul70]

pH 7.5
ammonia 0.25
nitrites 0
nitrates usually between 40-80 cannot get it any lower without changing loads of water and stressing fish.

lots of plants in to deal with nitrates.

 

[Gilli]

Theres your problem then - your ammonia should be at 0. 50% water change straight away and test again and then keep on testing and water changing every day until your reading is at 0. Cut back on your feeding until your stats are at 0.

I am assuming your tank is already cycled and that this is a mini spike? if not then follow the advise on the link below.

cycling a tank with fish in

 

[OldMan47]

Paul, changing water does not stress fish. That is an old story from back in the 1950s when we did not know any better. If I have any water quality problems, the first thing I do is a 90% or larger water change. As soon as I am done, the fish always look and act better than before the change. Never hesitate to do a huge water change if there is anything at all wrong with our water. As fish keepers, we really are water keepers not fish keepers. If the water quality is good, the fish will thrive.
An oil slick is often the result of feeding foods high in natural oils such as the typical flake that is high in fish meal. A quick way to remove the oil slick is to lay a paper towel on the water surface and then remove the paper towel. Often one attempt is all it will take to remove all signs of an oil slick.

 

[waterdrop]

Absolutely agree with OM47, it was the opposite of what we thought in the old days! WD

 

[Paul70]

50% water change done and fish do seem happier although some are displaying this kind of strange floating behaviour.

have read up on other forums and also watched videos on youtube and it seems that this behaviour is typical of tiger barbs. apparently the floating thing is them simply playing dead due to other aggressive fish in the tank (rtbs). it is part of the defence mechanism apparently. also some of the other behaviour which seemed like fighting could actually be mating and also the floaty standy on head thingy is also part of displaying.

anyway. water stats are still the same even after the water change but fish seem very active this morning and are happily feeding away on the pre-soaked pellets and flake i have given them.

good news is tho the oil slick has gone following the change so thanks.

 

[KittyKat]

Paul, remind me.. does your tap water have ammonia in it?

p.s. would be cool to see all the plants you got, and very glad that you did get them

 

[Paul70]

my tapwater does have background ammonia of 0.5ppm after treating with prime at 1.5x dose so the biofiltration is coping with this background and also the bioload of the fish, just wish it could drop to 0. I guess it will eventually.

I am considering buying an external filter also to help with water quality.

Plantwise I have 2 vallisneria, 2 amazon swords and 4 cabomba. the cabomba were all 6" tall when I purchased them 12days ago. the longest is now at 24"!!

so it seems they are growing well and I have a nice amount of shade from the tank lights and the fish love it now. they have lots of hiding places and really enjoy playing around. the only downside is that it looks slightly overgrown and wild at the surface but i suppose in the wild environment nobody is coming along and pruning the indigenous plants are they so I suppose it looks kind of natural. I will endeavour to post a picture shortly.

 

[Paul70]

here is a picture of my tank currently. you can also see some of my fish but they are a bit blurred due to movement

 

[KittyKat]

Looks much better than before! You should experiment with trimming the Cabomba, it will make it grow bushier

(Did you add cardinals?)

 

[Paul70]

Yes I did add the cardinals. The other fish hounded them relentlessly for a few hours but now all get on well together. Apart from sharky who is typically aggressive but does not nip the others.
I will try trimming the cabomba to make it thicker kat, thanks for the tip

 

[Paul70]

following my 50% water change 2 days ago i have today experienced a nitrite spike at 0.25ppm. could my water change have kiled some of my n-bacs off. i used prime in my water but didnt let it stand for very long before adding it to the tank

 

[KittyKat]

following my 50% water change 2 days ago i have today experienced a nitrite spike at 0.25ppm. could my water change have kiled some of my n-bacs off. i used prime in my water but didnt let it stand for very long before adding it to the tank

No, more likely you had nitrite in your tap water (altho Prime would have removed some of it).