Aggressive Indian Loach

[Madarko]

hi - i'm new on this forum. me and my girlfriend started an aquarium up roughly a week ago, we got four neons, a pair of swordtails (male&female), 5 guppies (3female&2male), 4 balloon mollies (unknown sexes) a black and red shark and two Indian Loaches (or at least that's what it said on the tank in the pet shop - i found this page http/animal-world.com/encyclo/fresh/loac...dmoresLoach.php and the pic looks like ours - one was fully grown and the other was only a baby).

things got off to bad start to be honest - we didn't rinse the gravel, used untreated water from the bathroom and had the heater on too high - so many of the fish died in the first few days (including the younger loach) , but since the tank has settled down the larger of the two loaches has become very possessive of his little castle and will actively chase away intruders - and then chase all the other fish - just to make sure they know he's the boss.

anyway - we found one of the male guppies and one of the mollies dead the other day with their tails torn to shreds, and the other guppy has had his tail ripped up last night - but he's still alive.

so i am wondering - is it likely to be the loach killing everything - and if so, is there anything i can do to stop it - or should i just flush him to save the rest of fish

 

[mikev]

It is most likely the loach, but may be the shark too (not clear which species you have).

Tiger loaches (and yours is one of them, if you ID'd it correctly) are territorial and aggressive. You can keep them only with fish that is capable of resisting them (like other tigers, some other loaches, some sharks...), armored (large plecos), or fast enough to get away. Guppies are not fast.
Neons with loaches and/or sharks would not work well either. Keeping a small number of loaches (1-2) would make them even more aggressive than normally, with a sufficient shoal they will mostly deal with each other.



If you replace the dithers with danios and the tank is sufficiently large, this may work.
If the tank is small (you did not mention the size, but it should be a 30g+), you should not be keeping loach in it anyway.

 

[loachman]

It's possible it is the loach, as it is the most aggressive fish you have. Also, the loach will eat any dead fish so that could be part of what you saw.

The Tiger loaches are aggressive (there are a couple species that are all similar in appearance and temperament). I've also seen nippy swordtails before, and tetras can be nippy (although neons are generally one of the better).

Be on the lookout for infections and fin rot which is also common in new heavily stocked tanks. If the cause of the shredded fins goes away, they will heal readily in time.

 

[milkton]

usually if a certain species of fish are kept in groups of 2 or alone, they get aggresive. thats all i can say.