FW Compatibility Dilemma... Scats    4/4/06
Hi.  I have looked all over your site, Google, etc, and haven't found the answer to my questions, so hopefully they won't be too redundant.  I have a 30 gallon Freshwater tank with 10 Corydoras catfish (5 Trilineatus, 2 Paleatus, & 3 Bronze Aeneas) and 3 Dwarf Gourami (Colisa Lalia - 1 standard, 1 blue, and 1 sunset).  In addition I have 4 other tanks.  One is a 5 gallon with a spoiled rotten Betta (Splendens).
<Heee!>
A 20 gallon long sectioned into 7 spaces, containing 4 Male Bettas, 1 female Betta (also all Splendens), 1 Dwarf Gourami (Colisa Lalia neon blue), and 1 Honey Dwarf Gourami (Colisa chuna).  A 10 gallon sectioned into 3 spaces with, you guessed it, 3 male Bettas.  Finally, a 5 gallon corner tank with 4-6 Guppies in it.  Two of the Guppies are in sick tanks right now, so 4 is definite.  The other two, if they recover, will go back in as well.  They were in the 30 gallon, but the Dwarf Gouramis kept taking chunks off of their fins.  They also seem to really need the aquarium salt, which my Corys don't do well with.
<Agreed to all>
I had been using 1 teaspoon/5 gallons, but it wasn't enough for the Guppies.  The Corys were okay with it, but I wasn't willing to risk them on a higher dose.
<You are wise here>
The 30 is now salt-free, as are all the others, except the Guppy tank.  I consider the 5 gallon tanks full (stocking capacity).  I think 6 Guppies are max for the capacity of the BioWheel in the corner 5.
<Agreed>
The Betta in the other 5 gallon will not take any tankmates.  The last time I tried, he sulked himself into a lovely case of Velvet.  Long story short, he lives alone now.  The 20 long is full as well.  By water surface to air ratio I have space left, as well as by the inch/gallon rule.  However, with the extra filtration and dividers taking up space, I'm not comfortable with adding more fish into it.  The 10 is also considered full by both stocking ratios.  All the tanks are cycled.  I maintain the Bettas only tanks at 76/77 degrees.  The 20L and 30 are kept at 77/78 degrees.  My numbers are Nitrites 0ppm and Nitrates 0ppm (except the 5 gallon with the single Betta, which is 0 - 5ppm).  All the tanks are at 8.0 for Ph (stable), GH is 3 max, and KH is 9-11.  Ammonia is 0 in all but the 10 and 30 gallon tanks.  The 10 and 30 sometimes get a .25ppm reading, usually coinciding with my over feeding the little beggars (I'm working on that).
<Ah yes>
Water changes are 25 percent weekly in all but the 5 gallon tanks.  The 5 gallons get 50 percent changes weekly.  If I get an ammonia reading, I do an extra change and clean up the extra food.  Okay, by now I'm sure that you're wondering where-in lies the questions.  So here goes.....I wanted to get a couple fish to replace the Guppies in the 30 gallon, so I now have 2 Scat in quarantine.
<Mmm, no... too aggressive, gets too large... needs brackish to full marine conditions>
I made the HUGE mistake of not researching prior to buying, followed by the 'fish guy answered all the trick questions, so lets trust him' MAJOR screw-up.  Since bringing the Scat home, I have discovered that they are brackish fish, and I have no idea where to put them!
<Another tank... or... back to the shop?>
I think they are Scatophagus Multifasciatus.  They are silver with black vertical strips that run into/become spots on their sides.  They also have a bit of tannish color on the sides of their heads above and around the gills.  Their dorsal fins are similar to the Dwarf Gouramis, in that they (the fins) lay down and stand up depending on the situation.  Their dorsal fins are also black trimmed and pointed.   There were no Latin names on the tank they came from, just "Scat".  I'm praying I have the 5 inch fish and not the 15-18 inch fish.  Is there any way to tell for sure what they are?  
<Mmm, are easily discerned... see WWM: http://wetwebmedia.com/Scatart.htm
or fishbase.org>
Is it true that they have venomous dorsal fins?
<Yes>
If so, is it enough to kill a Guppy, etc?
<Mmm, yes>
  My husband wants me to put them with the Guppies (...already a brackish tank, problem solved.....).  Can I do that?  
<No... too different temperaments>
They're less than 2 inches right now.  They're smaller than my littlest C. Lalia, but bigger than the C. Chuna.  How fast do they grow?
<Slow if not fed well...>
We're talking about setting up a 55 gallon tank, but not for at least a year.  Can they be kept in a smaller tank that long?
<No... will suffer, likely die from renal problems...>
Are they even safe to have with our other fish?
<See WWM re... yes, with other brackish to marine animals of similar temperament...>
My quarantine/sick tanks are only 2 to 2.25 gallons each, so I need to figure out what to do with them when their 2 weeks are up.  Returning them is not a possibility.  They were purchased out of town (mistake #3).  I like them and would like to keep them.  They are quite personable already, and it doesn't take me long to get attached.  Any thoughts, words of wisdom, suggestions, or ideas would be greatly appreciated.  Thank you, in advance, for any help you can send my way!
<Great family of fishes... good with Monos, Datnoides, brackish to marine puffers, much more... all covered on... WWM. Bob Fenner>