10 replies to this topic

[fourdapostle]

Ok, here is one for those in the know, because I do not know what is wrong.
Tank 6ftx18x24h, fish 8 discus. Substrate just coursish gravel with only water sprite in the tank. Water perameters; amonia nil, nitrite nil, nitrates around 30, ph 6.6ish hardness 1k, ppm 77, temp 29-30. I use rain water off a clay tile roof (no concrete), 1/3 water change a week.
Discus have been in the tank since juvies 14mths ago now 17mths old, all are healthy and happy. I lost 5 peppies which I brought a year or so ago and they were growing well around 5-6cm and just started dying and disapearing, that was a couple of months ago all gone. After testing water and changed it as normal I also checked and cleaned eheim cannister filter nothing found within which would concern.
5 weeks ago wanted some cories to do a bit of a clean went to a sponser purchased 5 put in the tank the normal water ajusting time woke the next day all were dead.
I didn't have a nitrate or nitrite test kit but now have and have been testing the water for the last three weeks all as above pretty normal i would think.
I have breeding bristlenose so put 4 juvies in approx 4cm, found one dead this arvo. Dead fish look as if they should be swiming no obvious signs of anything.
I know this is a long winded post but if you have any suggestions I have not tried would much appreciate it. Why are the cats dying could it be something in the gravel?
David

[dazzabozza]

Why are the cats dying could it be something in the gravel?
David

Could be. How deep is it? Do you gravel clean? Has the substrate been disturbed recently?

Any signs of sunken bellies on the cats? Ever had a worm problem with the discus?


Daz

[fourdapostle]

Could be. How deep is it? Do you gravel clean? Has the substrate been disturbed recently?

Any signs of sunken bellies on the cats? Ever had a worm problem with the discus?


Daz

Hi Daz, Substrate not disturbed only ever had discus and peppies, but not really cleaned the gravel so to speak, and its 50-60cm thick. I did a clean of the gravel this morning will do another later in the week after the discus settle and keep doing until reasonably clean, then put some more cats in and see what happens. Never had a worm prolem with discus either.
It is the only part of the tank I haven't cleaned to the max so will let you know what happens...
Many thanks
David

[Shane_H]

How long have you been using rain water for?

Factors such as long periods of no rain (ie no water turn over) and long periods of warm weather (ie summer) has the same effect on your rain water tank as it would you rlocal pond in the park. Things can go stagnant, pathogens such as parasites and ameoba can collonise, not to mention any faecal contmaination that may enter through bird/insect/reptile activites. Does your tank have ANY gaps at all in the top? Is there a non-return valve on the inflow from the roof?

If cleaning the gravel doesn't work, I suggest slowly switching back to tap water.

Doing nutrient tests (ammonium, nitrite and nitrate) test is only one small selection of parameters that can affect fish health. If you use water other than what is supplied by watercorp, you may need to increase your testing regime to include things like metals (ie corrosion from tanks/gutters/rooves) or microbiological parameters (ie Amoeba, Ecoli, Ttcoli, Fstrep). Not only for your fish but also yourself, if you consume or bath in it?

[fourdapostle]

Some good points shane and worthy of consideration, which i will do. We drink the rain water with no side effects to us or anyone else who drinks it, (apart from the odd twitch and stagger) just joking, it is beautiful.
It is my belief that rain water storage tanks are a little different to the local pond in the park; ie there is no light getting to it as light to a pond therefore no alge, duck or bird waste neither cats or anything else for that matter but thanks for the input....I will look at some more checks....

[Shane_H]

I ment in the way that a pond heats up and has no water movement in summer.

But yeah, you're right, algae isn't an issue with no light. However, if there is any point of entry for other pathogens, the combination of no water turn over and high temperature can support thier growth. What is your rain water tank management regime like? have you de-sludged it before? Are you aware of any buildup of sludge in the bottom?

Sorry for all the questions, its just the use of untreated water sticks out to me. How long have you been using it for the fish? Is this the first summer?

[fourdapostle]

Yes this is the first summer and all seems to be fine except for the cats, however will look into what you are suggesting and get some advice on the subject. I am no chemist so I will look into it thanks
David

[dom]

i had a very sim problem with rain water tank lost hundreds of baby brislenose common and albinos .what i have found is where they breed partition a part of your tank and let them grow in there that is if there are any large fish in your tank ...back to the rain water i thought you couldnt get much purer water i was wrong ..ps brand new tank no sludge .....must be the rain water all the pollution i guess regards dom

[sydad]

Hi Dave,

I don't remember you mentioning in our discussion, that you used rainwater, or maybe I didn't hear properly. Anyhow, this could explain quite a lot as rainwater, although putatively "pure", often contains undesirable elements. I do not consider biological entities (bacteria/fungi) likely to be a problem, but chemicals are another matter entirely.

There are two main problems, the lesser first : viz.salt. You live fairly close to the sea, and it is possible that your rainwater, collected off a tiled roof, could contain significant quantities of sodium chloride.I seem to remember that you used a TDS meter, and that the results for salt were not overly high. Consider however that many of the catfish group, corydoras sp. in particular, are reputedly sensitive to salt, and I have personally noticed that bristlenoses react badly, albeit slowly to raised sodium chloride levels.

This brings me to the subject of "other" chemicals. Is your collection tank a metal one? If so is it galvanized (include zincalume coated here), and not colorbond on the interior. If the answer to this question is yes, and the tank is relatively new(less than 5 years), it is possible, quite likely in fact, that the water contains dissolved zinc and/or aluminium salts. Both of these entities are recognized as being toxic to fishes....particularly if the water is soft and/or acid. Older tanks tend to become progressively "passivated", or coated on the interior surface by basic oxy and carbonate compounds that will only cause problems (ie. dissolve) under acid conditions (could be a problem near industrial regions). Bear in mind here that years ago, when nearly all houses had their own (galvanized) rainwater collection tanks, zinc deficiency problems were unknown in the human populace. This has changed since the advent of reticulated mains water; the rare use of rain collection tanks (until recently), and the now common use of other than galvanized construction materials. Does go to show however that significant levels of zinc were present, and these could be sufficient to be toxic to fishes.

If your collection tank has a colorbond interior, and is new, there could possibly be a problem with organics leaching from the protective coating, though I must admit I have not seen any previous "evidence" of such.
If your tank is constructed of a thermoplastic material, it has had in it's base material, one or more plasticisers added. Although these materials are "legal", and regarded as "safe", there is evidence that they can cause problems. Much of such evidence is poorly documented, and as such is dismissed by regulatory authorities, particularly with regard to other than human health.

Consider however, that fishes are often more sensitive to pollutants than are we H. sapiens, and such topics are seldom adequately researched. One platicizer long commonly used in greenhouse materials, and in sunscreen lotions was dibutyl phthalate: considered of low toxicity, but was eventually shown to greatly inhibit plant growth... this in a substance used in greenhouses!
Also bear in mind that different species of fishes react differently to pollutants. Although discus are reputedly sensitive to some metabolic by-products, it was my experience over many years that they could tolerate (ie. survive) levels of some toxic compounds that quickly killed some other fishes.

The point I am (hopefully) making, is that it can be difficult to isolate the causes of some problems. On the positive side however, there is a solution, or at least a partial solution to most of the problems, or potential problems, outlined above.
That is the use of a molecular adsorbent (such as Purigen). These adsorbents are capable of removing many of the pollutants we find in aquaria; particularly those with relatively large molecules such as organic compounds. They are less effective with smaller molecules such as inorganic salts, but will often remove sufficient of these substances to reduce the likelihood of undesirable outcomes if they are present (be advised that regeneration will probably require other than the manufacturers recommendations to be effective).

A bit long winded, but hopefully of help.

Regards,
Syd.

[Shane_H]

Some vast volumes of wisdom there, Sydad.

Just to add to his comments...if a week or so of rigorous cleaning of the gravel doesn't appear to help the situation, and you are still keen on using the rain water for the fish, it may pay to have some analysis conducted on your water.

A lot of what Sydad mentioned was about leaching and corrosion of tank materials and coatings. For about $40-$50 you can have a sample of your water tested. It may even serve two purposes if your using it for drinking water...

I'd probably suggest analysing it for the seven toxicant metals: Arsnic, Cadmium, Chromium, Copper, Lead, Nickel, Zinc. Whilst only a couple may be used in your tanks construction, it pretty much costs the same to have the whole group analysed.

For your own drinking water purposes, it may also pay to ask for a routine microbiological anlysis (HPC, Ecoli, Ttcoli), also about $40. A lot of farmers have their water supplies tested on a regular basis as un-treated water can go bad quite easily.

If you're really interested, I'd suggest talking to MPL Laboratories in Myaree.

And do check the bottom of your water tank for any build up of sludge as this can harbour all sorts of chemicals. The list is really endless so good maintanence is the key. I'd even raise hydrogen sulphide as a potential issue.

Again...if it's not in the gravel, its in the source water. Safest option, just switch to scheme.

Cheers,
SHANE H.

[fourdapostle]

Hi Syd will speak with you tomorrow when I come around.
Shane yep looks like some more testing required, but my tank is poly, not steel or colorbond, so that eliminates a lot I hope, but yes tests to come....