Hi all,
Indeed, a cold water employee at my LFS explained that nitrates should be kept below 20 ppm otherwise there would be oxygen problems and many guides on the internet state that nitrate levels should be between 5-10 ppm for Rams, neglecting to mention WHY it should be between 5-10 ppm when they are known to spawn in water with 40-50 ppm concentrations.
There is a reason for all of these statements, and it relates back to the source of the nitrate and the conversion of ammonia (NH3) into nitrite (NO2) and nitrate (NO3). If you don't add nitrates to the tank water, any nitrates present either come from the source water, or from the conversion of the ammonia that has diffused from the gills of aquatic organisms.
Tap water
If we deal with tap water as a source of nitrates, if the water is high in nitrates it is unlikely to be low in carbonates, other nutrients or pollutants, and as such is likely to be unsuitable for keeping Rams in.
Nitrification
If we deal with nitrate as the end product of the nitrification: NH3 + CO2 + 1.5 O2 ? NO2- + CO2 + 0.5 O2 ? NO3-
we can see that nitrification is an oxygen intensive process and where the
"water high in nitrates, low in oxygen" idea comes from.
In non-planted tanks we can only reduce nitrate by water changes, therefore water high in nitrates has not been changed for as frequently, or in sufficient volume, to lower the nitrate levels.
This is where the old fish keepers saying "
the solution to pollution is dilution" comes from. This is incorrect, the solution to nearly all the problems that afflict aquarists is to add some actively growing plants, these immediately reduce, or remove, the majority of problems. We find that our nitrate levels decline with time rather than rise and will eventually start to limit plant growth and therefore we add nitrates (usually as KNO3).
The findings of Clive, Tom etc have been that nitrates themselves aren't damaging to fish health, even at quite high levels, so as soon as you have de-coupled nitrate level from both initial water quality and/or the conversion of NH3 and NO2 this "wisdom" becomes obsolete.
Bloodworm
dw105, why should frozen blood worms be avoided? I currently use these as provided by Food4fish.co.uk. They are gamma eradicated and are a bit of meat for the GBR's so I thought they served a good purpose.
It came from a post on the "British Cichlid Association" forum, a lot of people who's opinion I respect (Mark Breeze, quoted below) said they had stopped using them following unexplained deaths, and since they stopped using them they haven't had a problem.
I have learned this at my cost over almost 10 years studying Apistos, ive lost some cracking fish over the years. I never feed bloodworm to any of my 40 odd tanks of Apistos now........you are quite right it should have read "frozen", think i mentioned this later. I actually buy and feed live bloodworm by the kg when i can get it, as long as its small....
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http://www.britishcichlid.org.uk/phpBB3/viewtopic.php?f=6&t=1336&start=20>
The reason why frozen ones may cause problems is more difficult to find, I've never fed frozen bloodworms, but I always discard any live ones that aren't a very healthy deep red all over and wriggling. I've seen pictures/videos of people feeding frozen bloodworms, and a lot of them are very pale and/or banded and I think the problems may come if the worms are dead before freezing, and have started to decompose. Collection site and diet may also be an issue. I feed mine on dead leaves from the garden (I don't use any pesticides), but commercially I think they are collected from Sewage Farm outflows etc. where they naturally occur in huge numbers in oxygen poor, organic matter rich sediment.
There has also been some suggestion that the chitonous head capsules of the bloodworms can cause intestinal blockage but I don't think it is blockage issue because:
1. Live bloodworms don't seem to be a problem, and
2. Bloodworms (chironomid larvae) are part of their natural diet of
Apistogramma,
Mikrogeophagus etc.. From "Two new species of Apistogramma Regan (Teleostei: Cichlidae) from the rio Trombetas, Pará State, Brazil, Sven O Kullander; Efrem J. G. Ferreira (2005)
http://www.scielo.br/scielo.php?pid=S1679-62252005000300003&script=sci_arttext"
Bergleiter (1999) reported a mixed diet but mainly cladocerans, copepods, chironomid larvae and other aquatic insect larvae in stomachs of A. gephyra from the rio Xingu".
cheers Darrel