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Tetras (Neons & cardinals) dying one
by one in the dark in a planted aq. 8/7/08
I hope you can help. Please forgive the length, but I wanted to give you
all the info I could think of.
<OK.>
30g L, been up for about 8 weeks (cycled with seed filter from friends
established tank), custom hood with AHsupply 96w CF bulb (3.2W/gal),
eco-complete substrate mixed with fine gravel. Fluval 205 filter. Stealth
100W heater.
<All sounds good.>
Tank has the following plants (most of which are thriving): Cabomba (2
bunches of 5 stems each), Moneywort (4 bunches of 3 stems each), Melon
Sword, Chain sword (just a baby), Microsword (2sq in patch), Ruffle plant,
Wisteria (just finally establishing its fine submerged leaves - 1 bunch of
3-4 stems), Broad Ludwigia (1 bunch of 3-4 stems), small Java fern, small
Anubias nana, and a large bunch (about 15-20 long stems) of Anacharis (from
a friends established tank). Sounds crowded, but you'd be surprised how open
it really still is.
<At least some get pretty big -- Echinodorus osiris for example will quickly
take over a 30 gallon tank if it thrives; mature plants can be 50 cm tall
and 30 cm across! Echinodorus martii likewise.>
To this there's the following fish: 5 spotted Corys, 6 otos, 3 "mystery"
snails, 6 zebra danios, and originally 8 each Neons and cardinal tetras.
<Right, well one issue here will be temperature. To wit, Neons prefer cool
water, 20-24 degrees C; Cardinals need warm water, 25-28 C. There's no
"happy medium" at which both can be expected to do perfectly well.
Corydoras, Otocinclus and Danios are also cool-tropical fish, and will
thrive at 20-24 C (I'd go for 22 C). But that's too low for the Cardinals.
So one way or another, at least some fish are going to be heat or cold
stressed.>
The light is on a timer to cycle 6 hours on in the morning, followed by a 3
hour off break mid afternoon, then another 6 hrs on in the evening. Then off
for the remaining 9hrs overnight.
<OK.>
All was well, the plants are thriving, the fish too.
<Good.>
Then I added the anacharis about 2 weeks ago. Suddenly I'm missing cardinals
and Neons overnight, just 1 or 2. at a time. Never noticed any trouble with
the actions/attitudes of the tank mates, everyone pretty much sticks to
their schools. But the losses continued. Everyone looked fine when the
lights are on... healthy, active, feeding. It was great. Well it's a great
mystery alright.
<Well, Neons and to a lesser extent Cardinals can be plagued with "Neon
Tetra Disease" and will drop off one by one until the cycle of infection is
broken. But it is also possible the new plants brought in a predator, such
as a Dragonfly nymph.>
I finally started watching closer at night and I found that after the lights
been off for about 90 minutes (+/- 15 minutes) I notice a gradual and
frightening change. Both the cardinals and Neons lose nearly all coloration
going nearly white/clear.
<Quite normal.>
Then one or two of them start going bonkers and lose their equilibrium
swimming upside down, backwards and on their sides, barrel-rolls, tumbling
end-over-end, etc., then death.
<That is odd.>
Turn the lights back on and gradually (within 20-40 minutes) all coloration
has returned and activity resumes normally.
<Ah, now, this is curious. Have you checked how pH is affected by
photosynthesis? When plants photosynthesise they remove CO2 from the water,
allowing the pH to rise. When they stop, CO2 accumulates and pH goes down.
Alternatively, some (but only the minority) can perform "biogenic
decalcification", and I believe Anacharis is one of them. What this means is
that they remove carbonate and bicarbonate from the water as the source of
carbon for photosynthesis instead of CO2. This is why these plants prefer
hard water. Anyway, in the process the water loses its carbonate hardness
and consequently its pH buffering capacity. The net result will be that pH
will drop while these plants are photosynthesising, and the water pH will
also become less stable with regard to other pH altering processes.>
My water parameters have been rock solid since the beginning: Nitrite 0;
Ammonia 0; Nitrate "nearly" 0; kH 5deg; GH 12deg; pH 7.6; chlor. 0. I've
even tested right before and after a light cycle and saw no appreciable
difference. Temp stays between 78.5 and 80.5F.
<Do check the pH and carbonate hardness through the day to test my
hypotheses above.>
My thought were CO2 poisoning - but the zero change to pH leads me to
believe the CO2 isn't reaching toxic levels. Second thought - The plants are
using up all the available O2 (I'm not aerating) at night thereby starving
the smaller, more sensitive tetras. So I added a small airstone to the
corner of the tank and set a small air pump to kick on when the lights go
out (my timer has day/night outlets). It didn't seem to help.
<Leave CO2 off for a few days and see what happens. Won't harm the plants.>
Last Saturday night was the worst, within 2-1/2 hours three tetras gone
(down to 6 now, 2 cardinals & 4 Neons left), and all the fish (except the 5
Corys, 2 largest danios, and 3 largest otos) were pale. Even with nighttime
aeration.
<Hmm...>
So as a stopgap measure I retooled the timer to cycle the light and dark to
3 hrs light, 2 hrs dark ('round the clock). Two nights of success now with
no casualties... but even though there is the requisite "amount" of light
and dark I cannot imagine the rapid time cycles are any good for either the
fish or plants long-term.
<It isn't good for the plants; they need a certain length of time simply too
start photosynthesising, and 3 hours won't be enough.>
My next attempt will be to get a larger air pump and drive an 18" bubble
wand across the back of the tank rather than the small airstone driven by
the smaller air pump. I know this will drive out more CO2 to the detriment
of the plants (though probably not too much), but it should eliminate the
worry of CO2 poisoning, and should add O2 in the dark for the plants and
fish to (hopefully) share. Also, I'll be raising the filter spout up closer
to the surface to provide a little more surface agitation (currently its
about 2in below with no agitation).
<Not sure this is the issue.>
Finally, since this all started after adding the fastest grower in the
largest number/mass plant-wise (the anacharis). It's possible that plant
addition might've pushed the balance over the edge with respect to CO2 and
O2 respiration. So I'll be pulling that out and trimming it back to a more
manageable (2-3 bunches of 4-5 "short" stems each) size.
<Hmm...>
Hopefully then I can gradually return to slowly extending the light/dark
cycles to a more natural rhythm and keep my fish healthy and my plants
growing.
Any thoughts? other suggestions? etc? Anything I missed?
Mark
<Cheers, Neale.>
FW Cardinals, and something sinister- Stressed Fish Start To Have Problems
06/15/08
Hello WWM crew. First, I have to thank you again for this great resource-
your time and
expertise help so many people. You helped me a great deal in the past with the
curious subcutaneous worms plaguing my Cardinal tetras. Thank you so much.
< Thank you for your kind words.>
Treating the tank with Seachem's Cupramine at ¾ of the recommended FW dose
worked well; every single Cardinal pulled through! The only "casualties" were a
clutch of eggs that my male M. altispinosus decided to eat despite his mate's
valiant efforts at guarding them (they are usually a great breeding pair).
That being said, something sinister seems to have creeped into the tank. About a
week ago, I found a Cardinal looking emaciated and lethargic. He had hidden too
well in the plants and I had not found him in time to effect any positive
change. A few days later, a heat wave struck. When I arrived home, the
temperature was close to 90 degrees F! Everyone was either floating oddly or
lying on the bottom. Off with the lights, on went the AC, and I floated sealed
bags of ice on the surface. Remarkably, everyone recovered
fully except for one large female Cardinal, who I found the next morning.
Yesterday, another Cardinal started "shedding"- imagine a dog shedding its winter
coat,
but a fish shedding its scales. He also appears to have popeye! This evening,
another Cardinal appears to have the beginnings of popeye. One Cardinal could
have been an isolated incident. The second could have been an accident. But four
Cardinals within a little over a week? I DON'T like those odds.
Everything sounds environmental, but- Ammonia = 0, Nitrite= 0, Nitrate=0
(aquarium is long established/cycled, I just have a lot of very happy plants),
water is soft (RO mixed with tap, cleaned at least weekly), pH is 6.6,
temperature is 82 degrees F. Is there something else that I should be testing
for? Could there be another connection between these incidents? There has only
been two recent change to the tank: one day before the first Cardinal's death, I
added a new Fluval canister filter to the existing tank filtration (which
remains in place), and I had begun using new ferts for the flora (iron enriched
"Plant Gro" by Nutrafin, since I can't find Flourish with iron locally- but I do
use Flourish root tabs). Coincidence, correlation or causation?
Tank mates include:
28 Cardinals (not that I can actually count them)
4 M. altispinosus
3 Otocinclus (Very fat and happy)
1 Longfin Bristlenose Plec
1 SAE
Last edition to the tank was the Plec, but I have had him for a long time and
transferred him to my main tank because guests always commented on how beautiful
he was. Everyone was quarantined for no less than one month prior to their
introduction to the tank. Their diet (in case it is relevant at all…) consists
of mashed peas, thawed frozen bloodworms, Nori (which I think they play with
more than actually eat), Spirulina flakes, Tetra granules and Nutrafin Max flake
food (and whatever eggs/fry tank mates manage to steal from the rams and the
Otos). I would greatly appreciate any insight into my Cardinals' plight- advice,
guidance, suggestions, musings, criticisms or reasons why atmospheric pressure
is conducive to the integration of pachyderms into society.
Thank you so much, and enjoy your weekend,
Tianna
< Here is what I think is going on. During the heat wave your fish and
biological filtration were stressed. Oxygen levels were low and metabolism was
up. Not a good combination. You fish may have somewhat recovered but the stress
made them vulnerable to bacterial infections. For a short time period you
probably didn't have much biological filtration because the beneficial bacteria
died off during the heat wave. If nothing else their numbers may have been
affected. As bacteria start to colonize the canister filter they consume oxygen.
Some filters get to the point they consume all the dissolved oxygen going
into the filter. Make sure that the return tube forces the returned water to the
surface so it can be oxygenated. The infections can be treated with Furanace but
this will turn the water green, and the plants and bacteria will be affected. I
would recommend to isolate any diseases cardinals and treat them in a hospital
tank with Furanace type of antibiotic.-Chuck>
I am obsessed with keeping freshwater cardinals! I just can't keep them
alive! 5/13/07
Hi!
<Hello!>
Hope all is well with you. I have a question I hope you can help me with. I
have had reef and saltwater tanks for a couple of decades, and I do pretty well.
I even have a 600 gallon one in my kitchen wall!
<Sounds nice. Though if you prepare sushi in the kitchen, I imagine the fish get
rather nervous wondering if they're next...>
But I am obsessed with keeping freshwater cardinals! I just can't keep them
alive!
<I we talking those neon tetra look-alikes, Cheirodon axelrodi, or the
freshwater examples of the marine cardinals such as Glossamia aprion, the "mouth
almighty"? I assume the tetras.>
I have a 45 gallon tank with a sump. (an old reef tank). I had it setup with a
BioWheel, and gravel on the bottom. I suctioned the gravel monthly, did a 33%
water change monthly, and no luck with the cardinals.
<Cardinal tetras can be tricky for a variety of reasons, but once settled in
they're basically tough little fish. The main problem in my experience is Neon
Tetra Disease (NTD), which works its way through cardinal tetras at about 50%
mortality, i.e., if you buy 20 cardinals, and you get the dreaded NTD, you can
lose up to half of them. Better than neons, where you lose all of them, but
still annoying. Another issue with cardinals is they are all wild-caught. In
fact, they're the most numerous exported tropical fish from South America.
Anyway, by the time they reach the market countries around the world, they might
not have eaten for weeks. My guess is that healthy, well-fed cardinals are more
or less NTD resistant, but when weakened and cooped up in a retailer's aquarium,
they are far more susceptible to this disease. So as with any wild-caught fish,
buying when a new batch arrives can make sense, and then quarantining and
feeding on a variety of live/frozen foods makes all the difference.>
I then added an undergravel filter (I know....dumb idea, but I was desperate!)
<There's nothing intrinsically wrong with UG filters. They do a good job of
maintaining water quality. The problem with UG filters is their incompatibility
with aquascaping and rooted species of plants more than anything else.>
No luck. Nitrates off the chart. Dead cardinals.
<Odd, given how small cardinals are. They don't eat much (and don't need to eat
much, either). They're classic "pinch of flake a day" fish in my book. When you
say "off the scale" you mean above 100 mg/l? What is the nitrate level of the
water out the tap/faucet? I have to confess to keeping mine in rainwater with a
bit of tapwater added. Seems to work well.>
Someone suggested bioballs. Would not that make the nitrates even higher?
<Worth trying I suppose but I don't find nitrate removal systems in freshwater
tanks to be of much value. Freshwater fish don't care that much provided the
rise in nitrates is slow, and even between 50-100 mg/l you shouldn't get mass
die-offs of fish except with certain species (Tanganyikans for example). Simple
water changes are, IMO, a better approach to nitrate management, and the filter
is best devoted to biological filtration, i.e., ammonia/nitrite management
rather than nitrate.>
I have used Amazon rain additive (is that stuff any good?)
<Not really. Looks nice, but doesn't really do anything if you have hard,
alkaline water. In softer water, may help acidify the water a little, but
approach the concept of acidifying water with caution, as it's easy to mess up.>
No luck. PLEASE do you have an ideas? Thanks!
<Have a read of this:
http://www.wetwebmedia.com/ca/volume_2/cav2i3/cardinal_tetras/Cardinal_Tetras.htm
for some more ideas.>
Ron
<Cheers, Neale>
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