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First, basic info. pH should be neutral to low, 6.5 works great. Water should be soft but they seem to tolerate this better. Temperature is best at 78-82 degrees. Water needs to be clean, make sure tank is well cycled.

That's basic info you can get from someone who knows nothing about these fish. But there are other factoids that need consideration before you keep these fish. Seems like a lot but trust me, these fish are easy once you set them up right. You can even leave adults without food for a good week!

Here are the three major information points to consider. These three characteristics make for a unique fish that is often mistreated when one or more of these things aren't taken into consideration.

1.These are not aggressive fish.....Only if you fit in their mouth. Eating another animal would fall into the aggressive category but not the way we aquarists think of it. Mixing them with aggressive tankmates has been done plenty of times when plenty of space and distractions are produced for the other fish. I feel that aggressive tankmates should be avoided to have a healthy fish that acts normally. You also need to be aware of how large of a prey item the species you are keeping can eat.

2.These are piscivorous fish. Their name means 'hook nose' and that hook consists of many teeth used to hold fish prey (not slashing like the true, saltwater barracudas). They can be fooled into taking other food and even other prey (including live crawfish or even thawed out shrimp) but don't hold your breath and keep live fish on hand until you trick them off of them.

3.These are flighty fish. It can take as little as a light going off in another room to elicit a jump and startle and frantic darting. But there are solutions! First, for the silvery species (which is what are usually sold), cover is not such a great option. They occasionally use cover but prefer open water. Think; silvery fish usually swim (and are cameoflaged) in open water. Cover can actually make them nervous. Some plants are okay but most of these species are not ideal plant tank residents.
So, no cover, and (for best results) as long a tank as possible. These fish can move so fast (one of their impressive but dangerous traits) that they can kill themselves on the glass. This can even happen when feeding. A long tank gives a lot more room for them to avoid whatever random things frighten them and reduce the danger of damage or death. I've been told that my fish are remarkable in their lack of snout damage. The key: a tank at least 5 feet long. I don't believe in not sharing secrets when fish health is involved!

Also there are two health keys:

1. Fin rot. Of all the ways to lose these fish, fin rot is way up top. The stress of shipping is usually the culprit. I lost so many acestros after shipping because an otherwise healthy fish would have its fins rot to the base and the fish would die. The last time I had to deal with this I went against my usual belief that good tank conditions are way more important than medication. It was a last resort, but Fungus Eliminator actually worked wonders on some very sensitive fish. I've heard equally incredible cures are possible with Furan 2, Maracyn, and Melafix. That's up to you.

2. The other key would be feeding. These are some of the most parasitized fish I've ever seen in the pet trade and there's some cool biological background here that I'll get into later. The point: your feeding methods can actually help! For reasons I'd like to discuss more later, feeding feeders dry food makes for
1. a healthier feeder with more nutrients
2. time for the really unhealthy feeders to die
3. the possibility of reducing a feeder's parasite load

3 is controversial but has been observed in controlled situations in a parasite lab. Feeders drop parasites either because of some bulk effect, improved nutrition, or a reduction in parasite loaded food.

I'll get into how care differs between species next.
 

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For Acestrorhynchus there are 15 species right now. This may increase or decrease but, in my opinion, there are essentially 4 groups and that probably wont change. These 4 groups may have some taxonomic relevance but I group them mainly for aquarium care groups. Mixing of groups sometimes works and sometimes results in miserable or eaten acestros.

Group 1: Acestrorhynchus falcirostris. Why just one fish in this group? They're BIG, grow fast, and have HUGE mouths that can eat fish easily 2/3 their size. Affects potential tankmates. I have had them eat swordtails, shiners, small acestros (not on purpose! ), a flying fox, buenos aires tetras, mosquiofish, mollies, etc.

Their size can be over 10 inches but few people keep them in conditions that favor this growth. Tank space.......'nough said.

Here is a falcirostris;
 

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The second group are the altus/falcatus/lacustris/pantaneiro group. These guys are also BIG, capable of exceeding 10 inches but not as skinny.
They all have what is called a humeral spot behind their gills and they are thick fish. They mix well as a school and school with falcirostris well. Really neat, really tough (for an acestro), and quite easy to acquire are the falcatus. Altus are occasionally available as well. The others are on my wish list but should have the same care. A. grandoculis may be on this list but is more likely on the next list.

Here is are some aquarium falcatus;
 

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Discussion Starter · #5 ·
Here is altus. Not as much red as falcatus but very similar. (copyright amazon-exotic-import).
 

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Discussion Starter · #6 ·
Here is a wild falcatus all grown up. Trying to get one like this takes time and space! May not ever reach the glory of this wild state...
 

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Discussion Starter · #7 ·
Pantaneiro is an attractive species that German aquarists seem to have been keeping but I have yet to see it in the states (anyone help me out here? ). Beautiful fish, here is an adult;
 

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Discussion Starter · #9 ·
Don't ask me why, but A. lacustris is at the top of my fish want list. Other pics look pretty bland but this adult pic shows what the species is capable of;
 

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Recap: group one is falcirostris....BIG with BIG MOUTH
group two is altus/falcatus/lacustris/pantaneiro which are also BIG

These can live very peacefully together but can make the last two groups stress cases or snacks!

Group three, if full grown, may coexist with the first two but may hide a lot or eventually become a snack. These are the medium acestros and include grandoculis/guianensis/microlepis/apurensis/cachorro and possibly briskii, minimus and heterolepis. If you see anything other than grandoculis or microlepis it would be a surprise. Many of these are either synonyms for microlepis or are offshoots of microlepis. So these fish are all pretty similar (even though there is a confusing list of names).

As a rule these fish do NOT reach 10 inches and are quite unhappy over those that do! They are otherwise similar, rather colorless varieties of acestros that also sometimes have the humeral spot. Grandoculis have large eyes which does make them more interesting.

Here is a grandoculis;
 

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And here is one of my "microlepis"/"guianensis". I'm not 100% sure on the I.D.
Microlepis ranges throughout most of South America, as does falcatus. That leads to some variation and confusion.
 

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And the last group...the striped acestros

These are, as a rule, small. They include isalinae/maculipinna/nasutus and nasutus actually can get some size on it (but they are a rare find). Nasutus can reach 10 inches or so. (edit: true Nasutus is supposed to be under 4 inches, some confusion here. Probably because of nasutus being used for falcirostris' name).

Briskii and minimus also have a stripe or so but I have not seen them imported yet so don't know if they more closely resemble these guys or the group three.

As a rule, what is available is isalinae and they have been accidental food for group 1 and 2 in my experience. They are shy, but not as flighty. They also appreciate plants more. Of course, smaller fish are needed as food.

Here is an isalinae;
 

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Discussion Starter · #16 ·
Actually I won't stop here!!! I want to know what some of you think about some wacky net pics that almost don't seem to fit into the described species.

This is a stunning fish but it's gold and has black tail extensions. A variant on falcirostris?
 

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Discussion Starter · #17 ·
and what about this fish in the middle (the others aren't acestros)? A golden acestro? Geographical variant? Another stunning fish either way.
 

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well it is still quite early here, and that was a lot of information to take in, Thanks for an amazing post, I'll try to have another look when I'm more awake


 

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acestro Posted on Jul 31 2003, 06:01 AM
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Actually I won't stop here!!! I want to know what some of you think about some wacky net pics that almost don't seem to fit into the described species.

This is a stunning fish but it's gold and has black tail extensions. A variant on falcirostris?
Photo originates from a Sports Fishing page. Likely result of some nasty pirana biting off the lower caudal extension creating the illusion of a shark-like appendage. As for species? Not sure. Wish those photos were larger and the complex-species were not so complex!

acestro Posted on Jul 31 2003, 06:06 AM
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and what about this fish in the middle (the others aren't acestros)? A golden acestro? Geographical variant? Another stunning fish either way.
Not sure what the middle one is. Originally the photo submitter called it A. falcatus, but as we both know...doesn't seem to fit. As for the other two. Top is Rhaphiodon vulpinnis, Bottom: likely Hydrolycus schomberoides
 
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