Cynopoecilus - Cynolebias - (Leptolebias)Killing of the Hydra (rain-forest-tanks)
In an interesting series of articles ("Experimentelle Pharmakologie des Suesswassers")
in the German aquarium magazine, the DATZ0, Hueckstedt, G. in the Oct. 58 issue wrote
about the killing of HYDRA by a sudden decrease of the pH of the aquarium water. Using citric
acid or acid of wine, he decreased the pH value from a "near-neutral" value to 4.5, and that
killed hydra within 2 hours. A value of pH=5.0 also was effective and killed the hydra
within one day. He decreased the pH value from about 7.0 to about 6.0, after half an hour
to 5.0 and after another 10-15 minutes to 4.5.
This method is very useful in peat-tanks with very soft water and slightly acid water.
In such tanks one should never use the common "copper-method" because the copper easily will
dissolve in such waters and kill both hydra and fish. I have tried Hueckstedt's method several
times and always with good results. But in my opinion the killing of the hydra takes much
more time, than in Hueckstedt's tanks. I decrease the pH by using either sulphuric acid
or phosphorus acid. As indicator, I now use Bromo-cresol-green which changes from yellow
to blue between pH values of 3.6 to 5.2 (British Drug House Indicators. CN2011). I take a
certain water sample, normally 200 ml, add Bromo-cresol-green solution and titre with an
(unknown) solution of acid until the color changes to pure yellow. Then I count out the
amount to use for the tank (remember in all my tanks the water is slightly acid normally,
therefore there is no danger of too great concentration of carbon dioxide when adding acid
to the water). I then dilute that amount of acid very much with water from the aquarium and
add this further diluted acid very slowly (one to two hours) and distribute it into the water
by heavy aeration. Now the green and red hydra turn into a whitish color and after one day
they are dead. But as Hueckstedt, I do not increase the pH after the treatment. All my
various Aphyosemion, the Golden Tail Rivulus, the Aplocheilus lineatus do not take any
notice of the changed pH value. Some poor A. calabaricus that were in a large tank
which recently was treated with acid (phosphorous) using this method, now look much more
sound, than they did before. My Cryptocorynes and water ferns do not suffer from the low
pH value. Neither do my little red snail (I do not know the name; it is not the common
red Ramshorn snail). This snail, to my great surprise, used to multiply heavily when I
decreased pH by using phosphorous acid (why??). Daphnia survive also.
Two fishes did not stand the sudden decrease of pH: Aplocheilichthys pumilus
(perhaps A. katangae?) and Aplocheilichthys pelagicus (perhaps A. johnstoni?). Two
females of the latter died and only the removal of the other specimens of these two
species saved their lives.
The sudden decrease of pH should not be used in alkaline water. If the alkalinity
(SBV-Wert) of the water is above 2 ml 0.1 n HCl/100 ml, that will say more than 2 "units",
the fishes possibly will be killed by the carbon dioxide, which is liberated by the stronger acid.
Just a few words about the various species that I keep now, and the possibilities of
mailing eggs spawned by them:
Aphyosemion
- The common "australe" (lyre-tail): I only keep in order to use it in my crosses
within the old-world killies. The stock is mixed up with the "hjeresseni" (the orange mutation)
and not a pure stock. If you in your country have not had that "hjeresseni" but keep the
"good old type", Mullner and I will be very glad to have a few eggs in order to build up
a pure stock once more.
- The common aquarium stock of "bivittatum": I do not keep at present, but I know
where to get them if somebody is very interested in this species.
- The "calbaricus": (small, slender, sea-green species) are fed in order soon to
go into spawning. Last year the few eggs I mailed did not give live fry, so I am anxious
to try this species once more.
- The "calliurum": are spawning very plentiful. Yesterday a half grown female
gave away 100 eggs within a few hours. I only use the "ahli-type" in the spawning, but
as one cannot see what females are, you may raise both "calliurum calliurum" and "calliurum ahli"
from the eggs. The eggs often are "resting-fry-type". A very good aquarium species, also in
alkaline water on sandy bottom.
- "Coeruleum": are fed rain worms and surely will give away many eggs. Within the
few fry of 1958, which I raised only to keep the stock alive, I was surprised to find more
males than females. Very often this species gives us a large surplus of females. From eggs
that Jack sent me in 1958 I raised one male (eggs were frozen). He will be used in the
spawning in order to freshen up the stock. Resting fry is the normal condition, when eggs
are kept in water until ripeness. Use dry food or dry up the eggs.
- "Cognatum": the handsome red species is only kept in one or two pairs. These
are not quite ready for spawning, but will be ready within these months. Did any of the
few that hatched in Uruguay and Australia in 1958 live until maturity? Resting fry very
rarely developed in my stock since 1954. But in the big German aquarium book "Aquarienfische
in Wort und Bild" they write that resting fry often appear (alkaline water??).
- "Filamentosum": (often called "arnoldi" or "gardneri", the real name is not yet
known), the smallest species within the aquarium-kept Aphyosemion is only present in very few
pairs, but they are ready for spawning, if somebody would like to have eggs. Breeding is
just like "coeruleum". This species is very fitted for experiments of "resting eggs" and "resting fry".
- "Labarrei": perhaps the most handsome of all our Aphyosemions. As I did not
raise any for my own use in 1958, I found myself in the situation only to have one female
this spring. After a good spawning, she found a "leakage" and jumped out and was found
completely dry on the floor. Klementsen had a large surplus of big females, so I had 5
yesterday and spawning can go on. I never had any "resting fry" in this species, which
in many respects is not like the other Aphyosemion we keep.
- "Schoutedeni": Two females and two males are busy, but the females do not give
many eggs and also quite a large percentage catch fungus. In weak "incidental" light the
male is very handsome indeed. Slow-growing. Resting fry often occurs. This is the
type-species of Aphyosemion. I had this stock from Mullner in 1958 as eggs.
- "Sjoestedti": My stock of only 2 big males and 3 big females, which spawned
busy in 1958, is not as good as they should be. From the various batches of peat, which
I mailed in 1958 no report of any hatching came in. I then put water on all the rest
this spring and hatched one fry (a male). No resting eggs could be found in the peat.
Now I spawn the two teams on very fine mud and sieve the mud and collect the eggs. Very
many get fungus or decompose inside after 2-4 weeks. Methylene blue penetrates many eggs.
Something is wrong and I do not know where to get a new stock if these will not work.
But still there is a hope to keep this handsome species alive. Some eggs have been
transparent for more than 4 weeks.
Nothobranchius: I only had the eggs during the winter 1958/59. Now I have pairs
of "melanospilus" and "kuhntae". These two "species" are very close indeed, so I will
cross them when the spawning for you has been finished. The "palmquisti" gave only about
15 fry, all are males, also the fry with Klementsens "male-female" (see "SEX-RATIO"...).
I have to hatch more (if possible) from the various batches of dry eggs, which I still
keep from the 1958 spawnings, but as this species in 1958 only developed very few "resting eggs"
in the various broods, and the resting fry in eggs have been in this state for much too
long a time, it certainly will not be very easy to build up a new stock of this teasing
species. The "guentheri" is still in the egg-state, because many stocks of this species
are kept by other aquarists.
Epiplatys: The "bifasciatus" (see next issue of "Killie-letters") are restricted
at least for some months. The "sexfasciatus" have only males. One pair of the "chaperi"
are being kept to use in crossings.
Pachypanchax: many pairs are kept from the eggs that Jack sent in 1958. The
species is "homolonotus" from Madagascar.
Aplocheilus lineatus: I cannot find any females.
Procatous spec.: I still keep some, but most are males. I shall try to produce
some eggs if somebody wants this species. Very slow-growing at the temperature I keep.
Aplocheilichthys: possibly I can find a few eggs of "pumilus" (handsome) and
"pelagicus" later this spring. "Spilauchen" (see next issue) are restricted just as
E. bifasciatus.
Pterolebias: The very elegant and handsome "peruensis" which I got from Jack
as eggs in 1958 will be mailed as eggs in peat later. There are still some of the resting
eggs that were spawned in Philadelphia before 31 Aug. 58 developing. Some have already been
sent. This species as well as the "longipinnis" you will enjoy. My stock of "longipinnis"
sent to me as eggs from Foersch in late 1958 have only one female, but she is working hard
producing eggs for you. It will take some time before I can ship eggs.
Rivulus: Only "Golden Tail Rivulus" - a very good aquarium species indeed is
kept in my own stock, but aquarists here also keep the "cylindraceus". The GTR is spawning
very busy, yesterday one half grown female gave 65 eggs within few hours. I am mailing
this species now. I had much more males than females from the eggs from USA. Also my own
spawnings have mostly males.
Cynolebias: The stock of "bellotti" which Guevara sent me in Dec. 58 as
eggs are spawning fine and you soon can order eggs. Some already have been mailed.
"Nigripinnis " are still too small for spawning but I keep many "old" eggs, some of
these have already been mailed as experiments. Many eggs of "whitei" should be ready,
but as they have "resting fry", I have to wait for warmer weather. New stock is near maturity.
"Cynopoecilus": I keep a stock of adults in "ladigesi" that easily can be put
into spawning condition. Please order if you want this species. Very handsome if the
males are kept in very light tanks, in dark tanks the males brown and lack the handsome
green tint. But indeed it is a very small fish. The "melanotaenia" have produced many
eggs which are waiting for warmer weather in order to be shipped.
Jordanella floridae from Lewis came in alive over the North Pole late 58.
Eggs cannot be shipped as they are not tough enough.
These are the killies in my stock at this very moment. As it certainly is
not an easy matter to keep all species as adults in spawning condition I hope you
will excuse me, if the eggs of species that you need are not shipped at once. Anyhow
I shall do my best.
