It's probably one of three things...
1) Fin rot or a similar bacterial infection most likely brought on by the stress of the move and/or bad water quality. This will have melted away the ventral 'feelers' and now they've been lost. Is there any sign of blackening or white edges on any of the fins? What do you see where the ventrals normaly came out from? Test the tanks water and do a water change. If it does appear to be finrot, buy an anti-external bacteria med and dose the tank. Monitor water quality as these meds can effect biological filtration and make sure water changes are kept up with in future. Oh and also check the temperature of the tank. It should be about 76-78 deg F.
2) They got trapped somewhere and were damaged and ripped off. If you have a filter that could have sucked the fins into it this may have happened but it's the least likely. I would expect only one to have been caught anyway - not both. The danger with this is that you may end up with a secondary bacterial infection. Again, water quality is paramount. Take care to keep on top of water changes and treat for external bacteria or fungus if you see any sign of either.
3) The most likely is that they got nipped off. I'm guessing those 2 unidentified tetras are the culprits. Unfortunately, the only solution is to remove either the gourami or the two tetras. However, regardless of what you do about it, watch the gourami for signs of secondary bacterial or fungal infections and be prepaired to treat accodingly. Also, water quality is essential to reduce the chance of it getting infected. Make sure you don't overfeed and that water changes are being done regularly. Stress should be kept to a minnimum.
I'd also like to add that the ventral fins will grow back if they have not been completely removed. Even if they have, there's a chance they'll regrow. However, they will probably never again reach their original length and will most likely be uneven. The key right now is to watch for secondary infection and prevent it by keeping the water in supreme condition. If you can identify the unknown tetras (do they happen to be serpae or black widow/black skirt tetras by any chance?) that would help a lot. BTW, I'm assuming they realy are tetras - you haven't confused them with barbs or something I mean...
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