Re: 40 ltr Tropical tank needs bottom feeders/plecos?????
#8
Without knowing what your existing algae eating bottom feeders are on the basis of just the fish you have now you'd be looking at around 30 gallon minimum. Preferably more.
Fish bought from the shop are juveniles, babies, you need to account for the fish growing when making a stock list, the red tailed black shark will manage around 7" adult size given the space. Not given the space to grow and fish will become stunted, what this means is that their bodies stop growing but their internal organs do not, they die young of organ compaction.
It's not just about space for swimming too, though humane space is an important consideration (think of the multi billion gallon habitats they have in the wild), surface area for gaseous exchange, in a small tank, less surface area for O2 to be absorbed, low O2 levels in the water, O2 starved fish. Small water volumes mean less water to dilute toxins, do you test for Ammonia and NitrITE as well as NitrATE.
Not only that but proper companions are a consideration too, Guppies like hard water with pH in the high 7's, tetras like pH under 7 preferably around 6 for most species so you have one very uncomfortable (and now sterile) tetra species in there. Bettas require 10 gallons alone and putting them in with nippy tetras can result in disaster, his fins will be too tempting, nibbling will occur. The red tailed black shark will get big, and aggressive with age, wouldn't be suprised if he's eaten your tetras in the night.
Even if you upgrade there are uncompatible species there so may be worth a rethink and looking at rehoming of a couple. There's no reason you can't have a fantastic community in a 30 gallon with help and careful thought on what's suitable.
Fishkeeping really isn't a buy any species and put them together kind of hobby, just as you wouldn't put a rabbit locked in a room with a greyhound...
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