New Fish   8/20/06
Hi,
<<Greetings, Susan. Tom>>
3 days ago I got 6 platies, in a 10 gallon tank. They seem to be very aggressive with each other. Only two of them, but before it was only one.
<<New environments/conditions can bring this type of behavior out in some fish, Susan. A little early to tell if this is a "permanent" situation, though. My Sunburst Platies go through "phases" where they'll exhibit this type of behavior only to quit and go back to their normal activity, which is looking for me to feed them. :)>>
I feel bad because the other fish seem to be scared of them now.
<<Again, Susan, a bit early to tell.>>
The two fish are both females (I have 2 males and 4 females) and one of them seems to be picking on only one, and the other one is picking on the rest. But they won't pick on each other. They all seem fine, they look fine, I don't know why they're doing that.
<<Could be establishing a "pecking order", of sorts. Other factors may be involved here, however.>>
And another question: I'm not sure if one of my aggressive females is pregnant, but she had a bit of a bigger belly then some of the others, and she has a blue gravid spot.
<<With 'livebearers' such as Platies the females, almost invariably, are either pregnant or on their way to being so. Females are capable of storing the males' sperm inside of their bodies so they needn't mate every time in order to give birth. A single female, isolated from any males, can give birth three or four times (perhaps more) once she has mated. The fact that your female has a larger belly with a darkening gravid spot indicates that she's, almost certainly, pregnant.>>
She has a blue color to her, so is it just a beauty mark or something? The "gravid spot" is inside of her, so is it possible that she is?
<<I'd say this is not only possible but probable. On a sidenote, females close to giving birth won't be very tolerant of other fish, particularly the males. They prefer solitude and quiet (understandably) while the males have only one thing - besides eating - in mind, if you see where I'm going with this. Boys will be boys... :)>>
Thank you for your time.
Please respond as soon as possible this is very urgent for my fish.
-Susan
<<Keep in mind that all of your fish may look a lot alike but, won't necessarily behave alike. A dominant female may be showing the others, male and female alike, that she's going to "rule the roost" especially where mating is concerned. Usually, it's the males who pester the females practically non-stop but you might just have a couple of ladies who don't "play that game". Not at all uncommon, really. Keep an eye on them. If you have one that seems to pick on the others just because she likes to, she might have to be isolated. In the meantime, I wouldn't be too concerned. Best regards. Tom>>

FW Pecking Order   2/22/06
Thank you so much for your prompt advice.  I now seem to have a new problem. The death of my (slightly aggressive) male molly seems to have upset the
pecking order in the tank.  My three male guppies used to get along swimmingly, hanging around together as a defense against getting picked on
(presumably).  With the molly gone, the two biggest guppies are turning on the smallest and bullying him, and he is losing his beautiful tail, not to
mention the fact that he no longer swims with the other two.  I understand the behaviour, but don't know what to do.  He will be gone by the time I
quarantine another fish to help balance out the aggression.  Is he doomed to die?  And if he does, will the largest one then turn on the second largest
and kill him too?  Help! Kathy
<Move all the rocks and decorations around to new locations to set up new areas, then lower the water temp to 77 F to reduce their metabolism. Add a clump of floating plants or ABS black plastic pipe to establish a refugium for sick or injured fish to hide in.-Chuck>

Mollies
Hello, We have a small (15 gallon - high) tank with three mollies in it. It has UG filtration and an airstone (at bottom). Curious thing:
The mollies are always at the very top of the tank, something I have never seen before I moved them from a standard all glass 10 gallon tank.
<Hi Thom, Lorenzo Gonzalez replying for Bob-in-Indonesia... Mollies and their kin (guppies, platys, etc.) are surface fish by nature, just look at the shape of their mouths. Just right for eating insect larvae off the surface... A little factoid for your museum, your Mollies are a close relative of the 'mosquito fish' cultivated in some parts of the world to combat mosquito-borne plagues... Anyway - the new 15 high is quite a bit deeper than their old home, and unless there's interesting stuff throughout the depth of the tank, they really won't explore much...>
I'm writing as I just came across "Ask Robert Fenner a Question" and thought I might. 
Thanks,
Thom Smith, Curator
<Any time. Bob will be back from safari in about 10 more days. I've been answering his 20+ daily emails for several days now... boy is it hard, but rewarding labor! Regards, Lorenzo>
THE BERKSHIRE MUSEUM
Check our site: http://bcn.net/~aquarium/Museum.htm

Guppy and Starfish Questions
Hi there!
<Cheers.. Anthony Calfo in your service>
I seem to be emailing you on a weekly basis these days (sorry) but the more we get into this hobby the more strange and unusual things happen!
Anyway, my first question relates to our tropical tank. One of our guppies has got the hots for a silver colored platy. 
<what a cheeky little monkey>
He pursues her around the tank relentlessly, trying to make her see just what a God's gift to fish he really is, while she plays hard to get! I assume that this relationship is doomed and he will suffer forever from unrequited love. 
<are you still talking about fish  or do know my high school sweetheart?>
However, if they do manage to get it together what will the results be? Gatties or Pluppies? 
<actually a fish that looks like Buddy Hacket with a tail>
Or could there be another reason for his amorous advances?
<sure... he may just wants to cuddle...hahahahahahhahhahahhahah! Ahem, I mean...no, I think you've got the general gist of his intent. They may not even be able to produce viable offspring/hydrids>
My second question relates to our reef tank. One of our Fromia starfish seemed to expel something from its underside the other night. It was orange in colour (same colour as the starfish) and resembled two hands (or two starfish even) stuck together. It measured about 0.75cm wide and 0.5cm high. It was carried around in the tank by the current and settled briefly on some live rock before disappearing into the reef. The "legs" didn't appear to move during its brief stay on the live rock. Have you any idea what this thing is?
<under stress...some echinoderms do release part of their innards. Perhaps this is the case, but I honestly have no clear idea>
This hobby just gets more and more fascinating! Thank you for all your help! Lesley
<kindly, Anthony>

Swordtail Disappearing Act?
Hi there I am new to this so I was wondering if you can help. 
<<Hi, I probably can. Hopefully in time!>>
I recently purchased 5 swordtails 3 male 2 female (did not know this till I got home). This morning all was ok, this afternoon one of the males has disappeared without a trace. 
<<Very likely driven right up OUT of the tank by one of the other males. Which, by the way, really must be returned for another female, or things could get very ugly for the girls.>>
The swords are the biggest fish in the tank are all males are similar in size. Where has he gone and has he been eaten? Jim
<<Check around that tank VERY carefully - cannot stress/emphasize how easily fish get into the smallest places. If you find him in time you might be able to revive him. I feel he has MOST CERTAINLY been driven out of the tank. Check even the weird places. If he just died in there you would see the other fishes nibbling on his rotting corpse. Marina>>