Popondetta Furcata (forktail Blue-eye) Are They Aggressive?

[B2k2]

Hi,

I bought 4 Poppondetta Furcata on monday and seemed to be doing ok, but now I have noticed that on a couple of them the bottom of their caudal fin seems to be nipped. Also I found one of my WCMM dead this morning and one with the same damage to its caudal fin. It only seems to have happened since I introduced the new fish, I thought they were peaceful. Can anyone shed any light on this for me?

 

[Lateral Line]

Pseudomugil furcatus, (not Popondetta furcata), is a peaceful shoaling fish.

Your tank seems heavily stocked, and there are other "anomalous" indications. It is difficult to point fingers when you have shoaling fish kept singly, (SAE), and a basically overstocked tank, (which leads to uncharacteristic behaviour).

 

[B2k2]

Pseudomugil furcatus, (not Popondetta furcata), is a peaceful shoaling fish.

Popendetta furcata is what this fish was named as in my LFS, found a good page on the net about this fish that explains how the name was changed over the years. have a look here.

It is difficult to point fingers when you have shoaling fish kept singly, (SAE),

SAE's can be kept singly as many members of this forum do. Also profiles I have found on this fish also advise that they can be kept singly, see here. I have been observing my SAE and he leaves everything alone except for when my oto's try to get to the cucumber when he's there.

I'm pretty sure my tank really is not overstocked to be honest as it is heavily planted and overfiltered. I don't think the inch per gallon rule counts here. If you are refering to the amount of shrimp I am keeping then as they are very low bioload I do not think they effect my stocking that much.

I have been keeping a close eye on my fish and have come to the conclusion that the furcata's are doing this to themselves. I have noticed them copying the behaviour of my LFWCMM which chase each other, display their fins at each other and body slam all the time. LFWCMM seem to be quite aggressive to each other and as far as I can work out from research on the net and comments from LFS's this is normal behaviour for this fish. The furcata's are shoaling with the LFWCMM so maybe they think that they are the same. But I went to another LFS yesterday which I know keep alot of furcata's, quite a few of the fish had the same damage to their caudal fins.

As only one has not got this damage maybe this is a female and the others are male. I'm thinking that maybe they are fighting for the attention of the female. All four seem to be doing ok even with the fin damage and hopefully they will grow back ok.

 

[Lateral Line]

>>> can be kept singly as many members of this forum do.

Yes, but this does not alter the fact that in the wild it is a shoaling species, and shoaling fish kept singly often exhibit unpredictable and atypical behaviour. Shoaling fish not in a shoal are stressed. This stress manifests itself in many different ways, which can include aggression.

>>> the inch per gallon rule counts here

The inch per gallon "rule" is not a rule, it is a guideline to the absolute maximum a tank should be stocked. I believe 1" per gallon to be overstocked, but that is simply my view. Tanks stocked like that look like fish soup to me.

A quick summing up without including any of the shrimps yields over 30 inches of fish there.

As they are new in the tank, a certain amount of rivalry often happens as the fish in the smaller group vie for position in the groups pecking order. This can last a few days to a week. It usually settles down and little damage is done. Could be what you are seeing here.

 

[The-Wolf]

I have kept psudomugil furcatus and I can tell you they can be mean little blighters.
they are also very demanding of water conditions and will easily die if these conditions are not kept strict.

Popondetta is not a valid taxa in this case; even J.T. Nichols (the original namer) has aggreed this point.