Fish Compatibility Combination Queries

[CFC]

Dont forget that with Oscars and rays you wont be able to keep many live plants (if any) as both fish will pull up and destroy plants for fun, also the fish and their diets are much different and create a lot more waste than the fish you have previously kept so larger and more frequent water changes are needed. With predatory fish 40% a week is the minimum ammount of water recomended to be changed and most ray keepers change 50% twice a week, as long as the water you use for changes each time dosent change then the water chemistry of the tank wont change, mine has a soild pH of 7.4 and a hardness of around 12dGH which never alters.

To house a single ray (not recomended, they do better in pairs or groups, i am still looking for a suitable male to join my ray) and a single oscar i still wouldnt recomend a tank of less than 180 US gallons though the 24" width isnt really ideal and a wider 30 or 36" wide tank would be much better.

 

[Paul_MTS]

I just did a water test on my big tank and the Nitrates are suprisingly 0. In my other tanks i get a slight reading around or below 20 but never 0.

Would this enable me do to less water changes aslong as nitrates stayed low?

I probable know this answer but thought I would check.

 

[CFC]

What test are you using? I would be very suprised to find a tank with fish in it has a nitrate reading of 0, especially if it has been filled with tapwater which usually contains a nitrate level of at least 5. Are you using any nitrate adsorbing media in the filtartion? The other reason for this of course could be that the tank hasnt yet cycled, i doubt this is the case but its a possibility.

However, even with a nitrate reading of 0 some water still needs to be changed weekly to remove dissolved organic compounds from the water column and replace buffering minerals which will be used up by humic acids released from the nitrogen cycle.

 

[Paul_MTS]

I use a hagen test. Just last week it was showing nitrate readings on another tanks test.

I'm testing regularly on that tank and everthings been fine, there's a few bags of media from other filters aswell dumped in the sump so should be well cycled.

I realise I would still need weekly ones but If that tank maintains 0 or very low nitrates surely to keep a ray succesfully I woundn't need to do big, often water changes, you won't realise how much the thought of doing 50% water twice a week on that tank scares me!!

 

[CFC]

Dont forget that your fish will grow and as they do they will create more waste, also rays themselves are very messy fish with large appettites so the nitrates will rise fast.
As i mentioned earlier nitrates are not the only reason to do water changes and you dont have to give a ray much of a reason to curl up and die, a change in pH, accumilation of dissolved organic solids or a increase in nitrogen compounds (ammonia, nitrite, nitrate) can all kill rays very quickly so large regular water changes and vacuming is needed to make sure this cant happen. You may not need to do 50% water changes twice a week as the ammount needed to be changed is dependent on how many other fish you stock and what size they are, a 200g tank with just a pair of rays can probably get by with just two 25% water changes a week but once you throw a few predatory catfish and oddballs with the odd large Cichlid into the mix you have to start doing more work.
Another thing to note is that it is not just rays that will require a higher level of care, many of the large wild caught species such as Pimeloid catfishes and predatory Characins are also sensative to water conditions so also need large regular water changes as part of their maintainance, big expensive fish are expensive and time consuming to keep.

 

[Paul_MTS]

Hopefully by the time they have grown enough to make me work more for them (litle gits!!) I would of finished college and working full time leaving me a few complete days a week to do water changes and other maintenence. At the moment it's a struggle to urge myself to do everything after college or work!!(no days free apart from holidays)

Hopefully this weekend I'm also upgrading to pumps on the tank as I'm quite disapointed with the current flow rate, it should improve filtration emmensly (sp)

Oh yeh just did a test on tap water and tested clear for Nitrates then did a test on the tank with pim pictus that just had a big water change and that was up to 5 mg/l in a few hours.