Aggressive Zebra Loach

[Kaybee77]

Hi all

I bought 3 Zebra Loaches for my community tank about 6 weeks ago. All has been going well until yesterday when I noticed one 'fighting' with the other and now he/she chases the other two around the tank nipping at them! I had read that they should be kept in groups of at least 3 but now that I have digged deaper into them I'm reading that they should be kept in groups of at least 5 =S Should I invest in a couple more or would this just cause more stress and fighting within the group? Would love to hear your thoughts on this situation.

I have a 130litre tank with:

6 Harlequins
5 Pearl Danio
4 Zebra Danio
4 Siamese Flying Foxes
3 Julii Cory
3 Zebra Loaches
2 Bristlenose Plecs

Thanks in advance

Kirsty

[Diana]

I see several of your fish are kept in smaller groups that might be optimum- here are a few ideas:

130 liter tank is about 34 gallons
How much floor space is there? What are the dimensions of this tank?

6 Harlequins- more would be better, but 6 is OK

5 Pearl Danio Probably hang out with the Zebras, if so, 9 is OK, otherwise some Danios will often get nippy in too-small groups.
4 Zebra Danio- See Pearls comments, this is even more so for Zebras. If they are not hanging out with the Pearls, then 4 Zebras are highly likely to start harassing the other fish.

4 Siamese Flying Foxes- Which species? Flying Fox (Epalzeorhynchos kalopterus) is non-social, and likely to attack all other shark shaped fish, especially their own species. Siamese Algae Eaters (Chrosocheilus oblongotus, (recently renamed from C. siamensis) is somewhat social, and will work in small groups or as singles. They get way too big to keep 4 in this size tank. There are other species (not as commonly available) that share some variations of the common name, and most are too aggressive toward each other to keep several in any but a very large tank.

3 Julii Cory- highly social- get at least 3 more.

3 Zebra Loaches- Probably the root of the problem is small numbers. The suggestion of "3 or more" usually comes from someone (a fish store) that would lose the sale if they suggested that 5+ was a better amount. Even the more peaceful Loaches run to a range of personalities and it is common that one in every crowd is a little pushier than average for the species. This range of personalities usually works better when there are more of the same species.

2 Bristlenose Plecs- If 2 males, they are likely to fight over territory. A male and female may get along, or 2 females are OK for compatibility. 2 BNs are too big for this size tank, though. Even one is pushing it, though it may work. They can be kept as a single just fine.

When these fish are young (and small) the tank size may be OK, but as they mature, and as you figure out the personalities and add more fish to fill out the schools I would not be surprised if you ended up with a tank at least twice this size.

[Kaybee77]

Thanks for the reply Diana.

The tank is 85(L) x 37(D) x 48.5(H)cm.

I have had the tank up and running for about 4 months.

The Pearls and Zebra danios all mix together, I did have 5 of each but sadly lost one of the Zebras the other day.

I also had 5 corys but have lost 2 in the past 2 months and do intend on getting a couple more, they are definitely my favourites.

The Siamese Flying Foxes are Crossocheilus siamensis.

The plecs are both females.

I used a 'Community Creator' tool on another fish forum and that is where I got my numbers from, it gave me a guide stocking level of 156cm and my current level is 146cm. Would you advise getting a bigger tank or moving some of the fish? Don't want it to be to crowded for them.

I contacted a local aquarium shop today and got a few ideas regarding my grumpy zebra loach and one of the tips was to decrease the temperature a little bit which I have done and he has calmed down but I will keep an eye on them over the next few days.

Kirsty

[starsplitter7]

Zebra loaches (B. striata) like warm temps. If you get three more, your problem will be likely solved.

[fredsky]

I'm new here, and worried about the fish I've ordered to complete my little 20 gallon high rainbowfish tank. I have 7 threadfin rainbows and 2 golden Inca snails, plus 10,000 unwanted tiny little dotted snails. Because of them, when I ordered the 5 Celebes rainbowfish, I also ordered 2 Zebra loaches. This was advised by the person on the phone. Of course. I know the 2 Incas will have to be moved. But I can't imagine another 3 or 4 Zebra loaches in this small and well-planted tank. The new fish will be shipped to me in 2 or 3 days. NOW WHAT??? Any suggestions are welcome. I can't kill these tiny snails any more. But it is a rainbowfish tank! Thanks.

[Diana]

Kaybee, any stocking level that goes just by the length of the fish is not a good one.
Fish produce waste based on their mass, which is more like length X width X height.
A fish that is twice as long as a similar fish is also twice as wide and twice as tall, so produces 2 x 2 x 2 = 8 times the waste, and has 8 times the oxygen need.
That sort of guide works OK when the fish are all under about 2" (5 cm) but gets worse if the fish are odd shaped, and as the fish grow.
A baby Kuhlie Loach that is only 2" long is only about 1/4" tall and wide, a really thin fish, very small mass. (5 cm long, but way under 1 cm high and wide)
A Cory that is 2" long may also be 3/4 of an inch tall and wide. A whole lot different from that baby Kuhlie Loach. (the same 5 cm long, but 2 cm or so high and wide)

Anyway, any of your fish that grow over about 5 cm (Siamese Algae Eaters and Bristlenose Plecs) will no longer fit in the waste/oxygen formula that went into stocking your tank.

Did you measure the tank to the outside or the inside? I get about 144-155 liters, allowing about 1 cm for glass thickness.
Tank size translates to about 40 (American) gallons, so this is not as bad a stocking level as when it seemed like only a 130 liter or 35 gallon tank.