Beiträge von FranciscoB

    There are several plants that I have been able to see thrive with my Metynnis spp. silver dollars, including my only specimen of M. altidorsalis (an adult male). I hope to get one or two female altidorsalis in the near future.

    In the photo, he is in the foreground, the two other specimens are male M. lippincotianus. Floating plants (in floating corral) are Salvinia, place there as food, and replaced regularly. Rooted plants (not food) are Cryptocoryne wendii 'bronze' on floor mat at left, Microsorum pteropus (on wood, -but can be left floating), and Hygrophila sp. (at left, also could be left floating). In the back, there is some Bacopa monnieri, but they do eat that plant too much.

    The same fish when he was in my other planted silver dollar tank, together with M. maculatus, and L. lipponcotianus. Same plants, plus rooted, Cryptocoryne usteriana. He is at left, bottom, partially covered.

    In all his splendor ..

    I am now in the process of consolidating my 2 Metynnis tanks into a single, larger planted tank, currently being set up. I will soon show it here!

    Good luck!

    For Central American tetras, there are several Astyanax species. Unfortunately, as far as I know, the only commonly available in the market are Astyanax fasciatus, and the blind tetras A. fasciatus mexicanus. Both of these are quite able of fending for themselves (usually) and are active enough to make a nice display. Other species are just never available.

    Sorry to hear of the problem, Maggi.

    I don't know what the issue may be be but it is possible that as you say, the hard water may be causing problems. It is worth considering further. However it is strange that the fish appear well for a long time, and then die without clear reason, within a short period of each other.

    Another issue I would consider would be to provide a more varied diet, specifically including other types of animal food, such as cut-up small earthworms. It may be that a higher variety may do them better. Nothing wrong with the mosquito larvae, but more 'meaty' foods may improve conditions? A self sustaining worm bin is easy to set up.

    I hope you figure it out, and good luck anyway!

    Absolutely beautiful!

    Thank you so much for sharing. Would you care to describe your setup in more detail? What are the plant species you are using (very successfully, by the way)?

    What tetra species is the group sporting an oblique line trough the tail and part of the body? Is it a species of Moenfhausia?, or a small Triportheus?

    Again, gorgeous setup! Thanks.

    [I just realized I did not translate to German...]

    Hi Daniel,

    Lucky you!

    That sounds like a wonderful tank!

    A few comments on the Tapajos biotope and the fish selection:

    C .. regani is quite common (that's my understanding) and a setting in which they are prominently represented doesn't have to be Tapajos-specific.

    H. pulchripinnis are also quite common and are primarily associated with the Tocantins Basin, not necessarily the Tapajos.

    I love your choice of lemon tetras (H. pulchripinnis) as the numerous schooling fish that complement the rest of the setup. I love lemon tetra and currently have a smaller school (15 or so) in my tank that is considerably smaller than you plan on. Although Regani pike are much more peaceful than other species in the genus, they still grow tall (14cm or so) and I'm afraid some of the lemon tetra won't get past them unless there are plenty of rocks and wooden hiding spots , but also with these hiding places. That would be my only consideration regarding the stocking.

    My only other comment would be to add some plants that may be attached to the tops of branches (thicker ones, not thin ones), although I realize that this would be difficult to do in true Tapajos fashion. But it would provide refuge for the little tetras and improve the overall aspect of the setup.

    Sounds good! I look forward to seeing it. Good luck with that and thanks for sharing.


    Hi Daniel,

    Lucky you!

    That sounds like a wonderful tank!

    A couple of comments on the Tapajos biotope and the fish choices:

    C.. regani is quite widely distributed (that is my understanding) and a setting featuring them prominently does not need to be Tapajos-specific.

    H. pulchripinnis are also rather broadly distributed, and mainly associated with the Tocantins basin, not necessarily the Tapajos.

    I love your choice of lemon tetras (H. pulchripinnis) as the numerous schooling fish to complement the rest of the setup. I love lemon tetras and currently have a smaller school (15 or so) in my tank, which is considerably smaller than what you are planning. Although regani pikes are considerably more peaceful than other species of the genus, they still get large (14cm or so) and I fear that some of the lemon tetras may not be passed by them, unless there is a lot of rocks and wood hiding places, but even with these hiding places. That would be my only consideration about the stocking.

    My only other comment would be to consider adding some plants, perhaps attached to upper parts of branches (thicker, not thin ones), although I realize this would be difficult in a true Tapajos manner. But It would add refuge to the small tetras and help enhance the overall aspect of the setup.

    Sounds great! I look forward to seeing it. Good luck with it and thanks for sharing.


    Only one animal, or as a group in a very large tank. In their natural habitat, adults are schooling fish, and in addition to that, they are migratory as part of their reproductive seasonality. They do so in large shoals.

    Perhaps the INTRAspecific aggresion we see in aquaria (almost always too small) does not occur as much in nature, or, alternatively, it may play a role in the social context of migratory behavior.

    But in commonly sized aquaria, more than one specimen will almost always result in a lot of picking and hierarchy fights, usually to the demise of a lesser specimen (small or less self assured).

    It is great that these fish exhibit little to no- INTERspecific aggression, and generally are rather tame towards other fish, both larger and smaller. Mine (20-25cm) is very docile (though seeks food very aggressively) and friendly, and a delight to have (meet him/her below). She/he likes to be pet on the top of the head.

    Hi Axel,

    +1 about the (otherwise good pictures) not showing well the issue.

    In my opinion, the exophthalmy (googly eye) may not be related at all with the tumor-like ailments, nor the flashing that you are observing on your fish. I think they are separate issues happening at the same time.

    Regarding the growths, I am afraid that indeed, it may be what is often called 'fish tuberculosis'. Very likely, this came into the tank with the recent introduction of the platys, even if those may not have displayed it. I say that, assuming that your aquarium had the rest of the fish for a long while in good health, prior to the platys; I don't know the history so I may be wrong. My opinion is that 'fish tuberculosis' is a general term used to describe ailments caused by actually a number of different agents, and not a single causing microorganism. If viral, there is no effective treatment. If bacterial, it should be treatable but you may need a combination treatment, as the actual agent is not known to you.

    Regarding the googly eyes - In my experience this can occur from either a physical injury to the eye (somewhat uncommon), but is more frequently due to chronically insufficient water changes leading to accumulation of nitrate to high levels (beyond 20ppm). The fact that two fish showed it argues against physical injuries separately on each. Again, you know the history of water changes and nitrate in the tank, but I would recommend to check that. I have been able to improve the health and appearance of googly eyed fish I have rescued, just by providing excellent water quality via frequent and large water changes as a routine (for me, no less than 50-70% weekly). It takes months but it does recede, even in cases of whitish films over part of the eye.

    A different observation is that the ideal conditions for long term health of the altum and Manacapuru angels and that of the platys are at odds. Softer, lower pH versus harder, higher pH. It is true that both are adaptable (especially the platys), but they are not an ideal combination. Something to think about for the long term. Better to look for vivid colors among more compatible species.

    I hope others are able to better diagnoses, especially treatment suggestions. Good luck!


    One possible explanation; there could be others - If the rain water collects water that has ran over the roof of a building, the roof material has every chance of altering the pH of the collected water. Rain water collected in the open (not after running over a roof) should not be affected and provide a good comparison.

    My planted Metynnis spp. aquarium continues to go strong, and the fish continue to now eat my plants. Three M. maculatus in this tank are 22 years old, and the single M. lippincotianus in the picture is ~ 4 years old. I had to take out three fish to another tank, due to excessive harassment of the adult males to the single adult female. Eventually they will be put back together in a larger tank.

    If you like Sagesalmier (Metynnis, Myleus, Myloplus, Tometes, etc.), and have found ways to keep them in planted tanks, please do post images! Many of my colleagues keep telling me it is not possible. What do you think?

    Cheers, Francisco.

    Hi All,

    I appreciate and respect your views and agree with them, up to a point. And I very much thank your for showing your fish and sharing your experiences, which I value highly.

    Yes, I would rather have a large school of Hemiodus in a very large tank. However, for me, that is not possible for several reasons:

    Regarding the Hemiodus-

    1) I have only seen these fish for sale twice in my life, once at a "natural" aquarium in Cali, Colombia, and the next time was when I bought these fish (x4) at a store in New Jersey. Never again. Increasing the size of the school seems i possible, both because of where to get from, and because the size of the tank; 2) Under my care, they have grown from ~ 5cm to ~ 14 cm in close to 3 years, and have actually become calmer during that time; 3) when I bought them, they had injuries in their "noses", indicative of bumping into walls at the store tanks; the last time I saw any "nose" damage on my fish was at least 2.5 years ago, a few months after I got them. They are now larger, healthier, and calmer, they don't scatter around when I approach, and instead, come forward inquisitively to receive the food I offer or the taps on the glass they have learned to recognize as rewards; 4) If I were seeing any evidence of the fish not doing well, I would conclude that indeed they should not be kept in the 125gal tank I have. However, I don't see any evidence of that being the case. 5) Unfortunately, a tank larger than 6 feet (180cm) is just not possible at this time, unless it is built in place, and frankly, there are other priorities ahead of that.

    Regarding the Semaprochilodus (I believe this is what you refer to as 'night tetra') -

    This fish is currently 8-9 inches (20-23 cm), and also came to me as a baby (~6.5cm, photos attached). This fish eats from my hand daily and acts as a well-trained puppy. Never does it crash around, becomes startled or anything like that.

    Yes, I do know both Hemiodus and Semaprochilodus are schooling fish. In fact, Semaprochilodus are migratory too, which is something even the largest of aquaria cannot offer. I also know that Semaprochilodus can grow to a foot in length (30cm), as I have seen them as a food fish in Colombia, but I also know that it is not he bulk of them who reach that size, and that it takes a number of years to reach that size (about a decade to a foot long fish). But I don't see anything wrong about having them in a tank, which although not as big as it could be, it is not too small or cruel, so long as they look happy, act happy, look healthy, and have the signs of health to go with it. One day, hopefully soon, I will have a larger tank, but it does not seem to me their current situation is cruel or harmful to them, although it is certain that I could not have more fish in there.

    This is very different from the often seen large Astronotus in a 40gal tank, or red tail catfish in a 55, or the adult goldfish in a much too small aquarium.

    Again, with many thanks and respectful camaraderie.


    Hi SailFin and Ralf,

    Thanks for your messages and for posting beautiful images of your tanks, of your Hemiodus gracilis, and for sharing your experiences.

    I completely agree that I will need a larger tank than my 180cm (125gal). Unfortunately for now, that is what I have. The fish continue to do well, and to grow, although now at 7-7.5" (~14cm), they probably won't get any larger.

    They have actually became calmer as they have grown, now being quite chill, and allowing me to do water changes without much fuss. I do need to be careful, as they are big and fast. They eat almost from my hand.

    In October of last year I lost one to a tragic mistake on my part. Accidentally I left one of the lids of the tank open overnight, and the smallest of the four jumped out (photo atached). I was devastated and frustrated appreciating my error. Alas, things happen. It was the smallest, then a bit over 6 inches. The three left (2nd photo attached) have grown since by about a half an inch and are all at about the same size. They are my favorite fish.

    I guess not that many people keep them but they are very much worthwhile the effort. Super gentle, active and very beautiful. Cheers!

    Hi Basti,

    These are not books but icthyological works on various groups within the very large genus Crenicichla. Some are useful to aquarists like myself, but are aimed at actual icthyologists. At least the 1st includes pictures of live specimens, which may be useful to you. I believe the links should be live, as they are for me. Enjoy, Francisco. [One day, "the book on Crenicichla will be available!]


    [HTML] Phylogenomics of pike cichlids (Cichlidae:  Crenicichla ) of the  C. mandelburgeri  species complex: rapid ecological speciation in the Iguazú River and high ...

    L Piálek , E Burress , K Dragová, A Almirón, J Casciotta … - Hydrobiologia, 2019 - Springer


    [HTML] A review of the species of  Crenicichla  (Teleostei: Cichlidae) from the Atlantic coastal rivers of southeastern Brazil from Bahia to Rio Grande do Sul States, with…

    SO Kullander , CA Lucena - Neotropical Ichthyology, 2006 - SciELO Brasil


    [HTML] A new pelagic predatory pike cichlid (Teleostei: Cichlidae:  Crenicichla ) from the  C. mandelburgeri  species complex with parallel and reticulate evolution

    L Piálek , J Casciotta , A Almirón, O Říčan - Hydrobiologia, 2019 - Springer